Ask Chris: Is Fructose Really That Bad?

Paul from Facebook asks:

What are your thoughts on fructose? Is it really as bad as Paleo is making it out to be?

Dr. Robert Lustig has worked hard in recent years to demonize fructose, and his efforts have paid off. His YouTube video “Sugar: The Bitter Truth” has over 2.5 million views as of this writing. Lustig et al. claim that fructose is a uniquely fattening poison (when compared to glucose) that is as toxic to the liver as alcohol.

But is this true? Does the current evidence support this position? I’ve changed my views on this over time as I’ve become better acquainted with the literature, so I’d like to share my current understanding with you.

When it comes to fructose, calories matter

There’s no doubt that refined sugar – including fructose – can be problematic. But studies suggest that this is only true when calories are in excess.

This may be the most dangerous aspect of refined sugar: it leads to unintentional overeating. In a recent post on fructose, obesity researcher Stephan Guyenet points out that most people in these studies aren’t deliberately overfeeding. They are inadvertently overfeeding because they aren’t spontaneously compensating for the calories added to the diet via a large fructose- or glucose-sweetened beverage.

This doesn’t happen with fruit or other whole foods that contain glucose or fructose. When people add fruit to their diet, they reduce their calorie intake elsewhere to compensate. Not so with liquid-sweetened beverages like soft drinks. When people add a soda or two a day to their diet, they tend not to reduce consumption of other foods, and thus their calorie intake increases.

This is where fructose does appear to be more harmful than glucose. Although people don’t compensate for calories added via glucose or fructose, the fructose-sweetened beverages have more serious metabolic effects.

Is fructose uniquely fattening?

Dr. Lustig argues that, when compared to glucose, fructose is uniquely fattening. He claims that fructose is the most efficient substrate for de novo lipogenesis (DNL), which is the process by which the liver converts carbohydrates to fat.

However, Dr. Lustig relies on animal evidence that doesn’t apply to humans. There’s a big difference between mouse carbohydrate metabolism and human carbohydrate metabolism. When mice are on a high-carbohydrate diet that doesn’t provide excess calories, it’s common to see DNL rates of 50 percent and up. In other words, they are efficient at converting carbohydrates into fat, even when they’re not overeating. (1)

But in humans on an isocaloric diet (without excess calories), de novo lipogenesis falls into the range of 10 to 20 percent. The conversion of carbohydrate is less efficient in humans than it is in mice.

The research in this area is robust and uncontroversial. Nearly 50 controlled feeding studies have been performed on various aspects of cardiometabolic control. Most investigators working in this field believe that DNL in humans is negligible in response to fructose, and doesn’t comprise a significant source of dietary calories.

There’s another problem with extrapolating the animal evidence to humans in this case. The mice in the studies Lustig cites are eating huge amounts of fructose: up to 60 percent of total calories. You’d have to drink more than four 44 ounce Super Big Gulps a day to get that much fructose. Ain’t gonna happen.

According to researcher Dr. Sievenpiper in an interview with science writer David Despain at Evolving Health, the 50th percentile intake for people in the U.S. is 49 grams per day, which works out to 10 percent of total calories. Even the 95th percentile intake of 87 grams per day doesn’t exceed 20 percent of calories. That’s a lot of fructose, but it’s nowhere near the 60 percent of calories fed to mice.

Is fructose an evil toxin?

Dr. Lustig refers to fructose is a “poison” that is nearly as toxic to the liver as alcohol. But again, human evidence doesn’t support this claim.

In a recent paper, Dr. Luc Tappy and colleagues labeled acetate, fructose and different metabolites with stable isotope tracers so they could see how fructose is metabolized in the human body. (2) They found that 50 percent ends up as glucose, 25 percent goes to lactate and greater than 15 percent goes to glycogen. The remainder is oxidized directly (to CO2 through the TCA cycle) and a small portion – as low as 2-3% – is converted to fat via de novo lipogenesis.

Glucose and glycogen are easily processed by the body, and 2-3% conversion to fat is not significant. And while some have claimed that lactate may be problematic, a paper published more than a decade ago contradicts this. (Hat tip to Evelyn from CarbSane.) According to the authors:

The bulk of the evidence suggests that lactate is an important intermediary in numerous metabolic processes, a particularly mobile fuel for aerobic metabolism, and perhaps a mediator of redox state among various compartments both within and between cells… Lactate can no longer be considered the usual suspect for metabolic ‘crimes’, but is instead a central player in cellular, regional and whole body metabolism.

Translation: lactate from fructose isn’t a problem.

What does this mean for you and fructose?

Fructose-sweetened beverages like soft drinks and juice cause metabolic problems when calories are in excess, and studies have shown that people are not likely to compensate for the additional calories they get from such beverages.

This is why soft drinks and other beverages sweetened with fructose aren’t a good idea. That said, an occasional glass of fruit juice within the context of an isocaloric diet is unlikely to cause problems – unless you have a pre-existing blood sugar issue.

I don’t think there’s any basis for avoiding whole fruit simply because it contains fructose. As I’ve shown in this article, there’s nothing uniquely fattening or toxic about fructose when it isn’t consumed in excess. And since whole fruit contains fiber and other nutrients, it’s difficult to eat a lot of fruit without simultaneously reducing intake of other foods.

Fruit has been part of the human diet for longer than we’ve been, er, human. We’re well-adapted to eating it, and capable of processing the fructose it contains. (Unless you are FODMAP intolerant – but that’s a different issue entirely.)

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Comments Join the Conversation

  1. says

    Lustig is quick to point out that fructose isn’t bad unless in the context of excess calories, which is often the norm for those eating a standard western diet.

    It definitely does not apply to a whole food like fruit, which tends to be satiating and have a low energy density. Lustig specifically talked about that in the video.

    In the context of excess calories, fructose is “toxic” to the liver.

    • Chris Kresser says

      Lustig has been equivocal about this, actually. In other forums he has not emphasized the distinction between how fructose affects metabolism on isocaloric vs. hypercaloric diets. A lot of people are scared to eat fruit now because of his attack on fructose. Some may have misinterpreted his message, but I think in certain cases he has helped that along.

      • says

        I understood Lustig and Mercola to be against all kinds of fructose including fruit and that made me skeptical of their claims.

        Thanks for clearing this up Chris.

        • sandy says

          Mercola is not against all fruits. He advises those with health issues or weight problems to cut out all fructose until they reach a healthy state. With healthy individuals, to avoid juice and eat the whole fruit, but limit total fructose to 25 grams per day.

          • says

            You’re right, Sandy, and there is a very valid scientific reason for that. If you look at fat loss from a hormonal perspective, fruit is not helping the situation. Sure, there are plenty of good things about fruit, but helping with fat loss isn’t one of them.

            • Paleophil says

              There are dramatic differences between various fruits and fructose-containing foods. I seem to digest fruits worse than 99% of people, to the point where some people don’t even believe me when I tell them about the acne and foot/toe cramps I get from many fruits, but even I can eat an entire 17 oz (476g; 3.4 cups) carton of frozen wild Maine blueberries without significant problems and I’ve yet to encounter any reports of problems from wild berries by anyone on the Internet when I’ve asked or searched, and I haven’t seen a single study connect wild berries to obesity. It could be in part because a whole carton of wild Maine blueberries only provide 16.9 grams of fructose (according to data from Nutritiondata.com and http://www.livestrong.com)–well within Dr. Mercola’s limit, even at that large intake–and it also provides glucose that helps absorb the fructose, plus other things we may never fully understand. If wild berries give you problems, please let me know. I’d be interested to hear about how they affect others. The biggest (whole) fruit eaters on the Internet tend to be skinny rather than fat, and thus emaciation, rather than obesity, seems to be the biggest risk for heavy fruit eaters–especially for males. The sorts of fructose-bearing foods that seem connected to obesity are the industrially processed ones, like soda pops and manufactured fruit juices and fruit-flavored drinks, which was my experience, fwiw.

                • Paleophil says

                  Nice try. I get those symptoms from organic fruits free of pesticides. I rarely eat nonorganic fruits.

                • nasta says

                  organic fruit is full of pesticides, organic does not mean pesticides free. organic growers just dont use as many as non organic but it is as harmful as the rest. organic is a big business ;)

                • Paleophil says

                  @nasta

                  So are you trying to say all fruit is equally bad because both conventional and organic have harmful pesticides, even if some don’t give me any noticeable negative effects whereas others do? Should we just completely ignore personal experience?

                • julie says

                  I’m sure all of Nasta’s food is grown pesticide free, has never eaten GMO corn or heavily sprayed wheat, all water from pure mountain springs, no antibiotics. Amiright?

                • nasta says

                  @paelophil
                  absolutely not! i consider fruit good i just dont think that switiching to organic will solve pesticides/fungicides issues as its not pest./fung. free. i also think we shoud by no means ignore personal experienc but the opposite – focus on it. our bodies are the same yet so very different.
                  @julie
                  well first of all sarcasm is the lowest form of humor. And yes i do grow my own veg and fruit and when it comes to meat i think organic is better than non as it is applied in different way when it comes to animal. and yes julie one day i will have my own water and will be completely self sufficent and there is nothing wrong with it and if you wish you could be too :)
                  p.s. there is nothing wrong with modern medecine, antibiotics saved my life once but again i am trying to avoid pharmaceutical products as much as possible…

                • nasta says

                  @peleophil
                  just a thought to your problem with fruit…have you tired combining diet? according to food combination principles fruit shoud be eaten on an empty stomach preferably in the morning…may help…one never knows ;)

                • paleophil says

                  @nasta
                  Yes, I have tried food combining and no-combining rules, including eating fruit on an empty stomach in the morning, with no noticeable difference. The negative effects I experience are not so much with fruit in general as with certain fruits. Given that even I can tolerate moderate quantities of certain fruits reasonably well, I suspect that lots of folks who think they can’t tolerate any fruit could actually tolerate certain lesser-known ones reasonably well. I don’t know for sure, though–just a guess. A small number of fruits dominate the US market and were chosen more for shipping hardiness, shelf life, cheapness to produce and sell, bigness and attractive appearance than healthiness.

                • Stranger says

                  Nasta: I was struck by the strong reactions to your comment in this old thread, but my close friend mentioned that there might be quite a few pesticides in organic produce as well. Any particular resources you have which would be good for reading up more about this?

              • Mila says

                It’s not like people are eating whole fruits. No, they are taking the sugary parts and drinking just that, the JUICE. Dr. Lustig doesn’t have problems with fruits or grains. What he’s saying is that because people are so afraid of fat, companies have taken fat and fiber out of fast food/chips and loading it with sugar. Lots of sugar. This causes obsesity and problems like gout. Not because people are eating too much meat, they are eating too much supermarket bread/cookies/chips that are loaded with sugar.

                He’s saying, eat fruit in it’s natural form, not in juice form. Look at traditional asian diet. It’s whole grains, whole veggies, meat and very small amounts of fruit. Fruit is still very expensive in Asia. Also, fruits in asia tend to be lower in sugar.

                Visit any school today and see if kids are eating whole fruits, GOD NO. They are drinking some frankieberry-sugar loaded juice or sugar loaded chocolate milk. Also note that when people say bread is bad, what they really mean is, bread is bad because food companies load all breads with too much sugar.

          • Sean says

            Is this the same Dr. Mercola that is against vaccination, says don’t eat fish, pushes his expensive supplements, and thinks animals are psychic?

            • Loreli says

              I sure hope so! If you are eating fish from the Pacific Ocean, you better rethink your diet with all the stuff from Fukushima. BTW, animals are pretty smart. I wouldn’t be surprised if they are psychic :)

          • Ingrid says

            How is it possible to stay within 25g of fructose a day?
            What about the gorilla whose DNA is only about 4% different to ours.
            He lives mainly on fruit.

        • NSku says

          Lustig has never been against fruit. He points out that the fructose in fruit is accompanied with lots of fiber. His issues are with sugar added beverages and juices, Remember also he is a pediatric endocrinologist not just a scientist, and so he is seeing and treating children with obesity problems and is writing and lecturing from clinical experience. He has always been clear that it’s the dose (and lack of fiber) that makes the poison. and his shtick about fructose being toxic is just a way to underscore the way in which it is metabolized just like ethanol. It’s worth watching his original lecture and reading his book. I can imagine in the echo chamber of media interviews etc. distortions creep in. But the key points he makes hold true.

      • Martin says

        What do you make of Ray Peat? I have spent a lot of time recently reading everything he has written on his site + danny roddys site and the research seems really sound + there is so much of it spanning a such a long time I find it difficult to argue against his approach to eating.

        You are likely aware of the discussion between Paul Jaminet and Danny Roddy and it makes for some interesting reading.

        I am an athlete and have tried out Ray Peat style eating and seem to thrive on it. I am comsuming 2-3 litres of orange juice a day and at least 4 pints of milk along with seafood, cheese, liver, eggs etc.

        I would love to hear your views.

      • Manuel Herrera says

        I have read his book _Fat Chance_ and have seen some videos of him on You Tube. I never got the message from him that eating fructose in the form of fruit is toxic. He has encouraged eating the whole fruit and not blending or processing it. The insoluble and soluble fiber together are what slows down the rate of flux of fructose to the liver. See pp. 133-134 in his book and this video at 8 minutes or so. http://www.youtube.com/watch?v=Rj8uQUkhEAg

      • Phil says

        I just finished watching all of Dr. Lustig’s videos in their recorded sequence and noted it wasn’t until his later presentations that he identified “excess intake” as a critical aspect of his thesis. Also, he presents some concepts in a lay-vernacular that are misleading. Passionate as he is, I’d be somewhat skeptical of his agenda-driven thesis.

      • Joel says

        Regarding the paper you cited, Tappy & Le (2010), to say that it doesn’t agree with Lustig is not accurate. This quote is from the abstract:
        “The evidence is less compelling in humans, but high fructose intake has indeed been shown to cause dyslipidemia and to impair hepatic insulin sensitivity. Hepatic de novo lipogenesis and lipotoxicity, oxidative stress, and hyperuricemia have all been proposed as mechanisms responsible for these adverse metabolic effects of fructose. ”
        It then goes on to state that there is no evidence that HFCS is any more deleterious than sucrose – which is precisely the claim made by Lustig from clinical observation. Added to which, he also states that higher amounts of dietary fructose are the issue (stating that fruit is safer than fructose sweetened foods), and as we know “the dose makes the poison”, that fructose acts as a chronic toxin rather than acute, and the endocrine issues he notes (as regards insulin, grehlin and leptin secretion and feedback) are in fact correct.
        I jist think it’s good to be somewhat pedantic on these points, rather than polarising the issue.

      • Ryan says

        Lustig said in the video “When God created the poison(fructose) he packaged it with the antidote (fiber)”. I got that fructose from whole fruit is waaaaay better than fructose as a food additive.

        That said, I appreciate the fact that you pointed out that Lustig was talking about mice, not humans.

  2. says

    This seems very sensible and balanced.

    However, there’s one phrase you used that gave me pause: “Glucose…[is] easily processed by the body.” Normally, yes, I’m sure that’s true, but in cases of chronic excess, insulin resistance becomes a factor, right? Under these circumstances, surely the body has an increasingly hard time of processing glucose?

    And the inevitably-high insulin levels will prevent fat from being used for food, surely? Thus causing a vicious cycle of hunger-and-sugar-craving, right?

  3. says

    Just showed the 60-Mins “Is Sugar Toxic” video to my class today. Good article above btw. Lustig in this piece does say that HFCS is the same as sugar, neither being good, though in the past I know he usually singled out fructose.

    • James says

      He’s not singling out HFCS, he’s singling out fructose. HFCS and sugar
      both have fructose in approximately equal amounts. I think part of the
      confusion comes from people confusing fructose with HFCS.
      Both these statements can be true at the same time:
      1) fructose is more harmful than glucose
      2) HFCS is not more harmful than sugar
      because fructose is not HFCS and sugar is not glucose but rather
      both are made of a combination of the two.

  4. says

    If not sugar, what are the major food consumption contributors to the diseases of civilization among those who are not overweight? Does it almost all come down to bad grains?

    • Chris Kresser says

      Sugar (including fructose) absolutely contributes to western disease when eaten in excess, even in those that are not overweight.

    • Josh S says

      There’s also the 300% increase in PUFA consumption over the past century. Combine excess PUFA, excess sugar, and excess empty calories from refined grain “foods” and we have what we have now..

      • einstein says

        only the adulterated industrially processed and nutritionally worthless PUFAs. PUFAs in their natural form are not a problem, but a remedy.

          • says

            I remember a talk given by one of my Kinesiology teachers about a GNLD product called tre-en-en that is a blend of PUFA and sterols from wheat and rice grains. They came across it when researching how to combat chronic fatigue in the late 50′s (I think).

            This might be one example of PUFA’s being useful. I suspect another would be those PUFA’s we get naturally from eating lean, grass fed, grass finished meat. But then, we do get those in fairly small quantities, and they are balanced (when doing a good paleo anyway) between the n3′s and n6′s.

            Hope this goes some way to answering your question.

            Cheers
            George

          • Andrea says

            Oils lack the vitamins and minerals. Nuts contains the vitamins and minerals. Plus they are made by nature, not by men.

            LA(Omega 6) + B3, B6, magnesium, etc… = DGLA (anti-inflammatory) excellent for the skin.
            LA(Omega 6) taken without any vitamins and minerals = AA(very inflammatory in excess).

  5. says

    “You’d have to drink more than four 44 ounce Super Big Gulps a day to get that much fructose. Ain’t gonna happen.”

    I disagree with the “ain’t gonna happen” portion of this statement – I once worked with a man who came in in the morning with a plastic SuperBig Gulp mug full of, IIRC, root beer. He got another one at lunch time (when he also ate a Snickers) and one more at the afternoon break. That’s three 44oz sodas by 4pm.

    He then blamed his giant waistline on “the new baby” and the fact that he didn’t go dancing twice a week anymore.

    • Chris Kresser says

      There are always outliers, but as the statistics I quoted in the article suggest, even people in the 95th percentile of fructose intake are not consuming that amount of fructose.

    • helene says

      Many, many…I going to say most…drinkers of pop, drink easily 4 Big Gulps a day. They don’t drink water and rarely milk. MOST adults are also pop drinkers and/or koolaids & tea drinkers too. Hfcs galore.
      Maybe becuz you work with the small percentage if ppl who are health minded you don’t remember the epidemic of food ignorance that is the westernized world.
      Ppl are terrified of reducing fructose intake, even if they don’t recognize it as such.

    • helene says

      I seriously laughed at the ain’t gonna happen sentence also. In my world that sentence could exist. However I’ve often been noted for being quite unrealistic lol
      Sigh
      If we could just outlaw possession of sugars as are tobacco and alcohol, the world would be hella different for the other 85% of Americans who daily torture their cells. Parents would have to do their drugs, the sugars and junk foods, without their kids imbibing and ingesting too.
      Now THAT ain’t gonna happen.

  6. says

    Chris, I only partially agree with you regarding fruit and fructose. The problem – as with any foods or drinks – is the overconsumption of fruit, thus leading to excess fructose AND glucose (yes, fruit does contain both!). In the effort to eat “5-8″ servings of fruits and veggies a day per the ADA, people tend to lean more towards fruit, thus overconsuming fructose, glucose, and yes, calories. Also, one must remember that the consumption of fructose & glucose in any form contributes to bacterial overgrowth of candida and yeast and other non-beneficial bacteria in the intestines. About 85-90% of people in the US have some form or SIBO (small intestine bacterial overgrowth), or candida, or yeast, and don’t realize it. In my practice, when I am working with someone who has digestive issues (GERD, IBS, Crohn’s, etc), or weight loss, the first thing I do is take them off everything and only have them eat veggies and protein. The results have been amazing and astonishing! After a 21 day period, we gradually add back fruits that are elss than 10-15 grams of fructose, and of course, appropriate grains such as quinoa and amaranth. By this time, most people are so comfortable with just the proteins, complex carbs, and healthy fats that they don’t really want to go back eating “the old way”, including overconsumption of fruits! And it goes without saying, NO ONE needs to be drinking sodas or fructose-laden anything!
    Thanks for your response!

    • Chris Kresser says

      I also treat patients with gut issues for fructose intolerance, but I think the 85-90% of people with SIBO or yeast is an overstatement. The prevalence of SIBO amongst people with IBS is only 40-45%, so I think it’s unlikely to be 85-90% in the general population. I run stool tests, breath tests and organic acids urine tests on all of my patients with gut issues, and a significant percentage of them do not have SIBO or yeast. (In these cases, it’s a gut-brain axis problem.)

      The consumption of fructose and glucose does not necessarily contribute to gut bacteria overgrowth. Monosaccharides are absorbed high up in the small intestine, and are not likely to become food for bacteria further down in the small intestine. Fructose is transported across the intestinal lumen with glucose when they occur in equal amounts. When fructose is in excess of glucose in a food, it will not be well absorbed and in that case I’d agree that it will feed pathogenic gut bacteria.

      I don’t think that overeating fruit causes metabolic problems or gut issues for the most part, but once someone is overweight or had digestive problems, I do agree that too much fruit can be problematic.

      • Carol says

        Pulling this info from the CDC:
        •Percent of adults age 20 years and over who are obese: 33.9% (2007-2008)
        •Percent of adults age 20 years and over who are overweight (and not obese): 34.4% (2007-2008)

        That accounts for 68% of the population. What percent of the population that have gut issues are not in that 68%? It seems to me that given the overweight prevalence, fructose is a problem for more that least 68% of the population, unless your definition of overweight is different than the CDC’s.

        I am personally still in the overweight category, but thankfully, no longer in the obsese category. Unfortunately, my favorite fruit is the tomato (especially used in cooking), which has a fair amount of fructose. But of course, nothing like apple sauce!

          • Joel says

            No, you don’t add them together. You take the percentages eitherof thewhole or use the separate populationsas a base to calculate total percentage.For example is I had five alcoholic drinksof 20,25, 35, 40 and 45% alcohol, I wouldn’t have had 160% alcohol, but, assuming equal volume, 32% wouldbe alcohol.

            • Kim says

              Joel! Ah! That’s taking an average of 5 mixed drinks. Terrible math.
              If you have ONE soda drink that has 25% glucose and 25% fructose, that’s 50% sugar. You do add them together, because the percentages are based off the same total. The populations are based off the same total, not two different populations that you must account for.

  7. Brandon G says

    As a relative newcomer to the paleo world (mostly following Sisson and Wolf), my understanding of fruit hasn’t been that it’s totally forbidden. Rather, that eating it is both highly-nutritious AND spikes your blood sugar. So, it’s good for you, but eating too much will make it difficult to tap into your stored body fat, thus making it difficult to lose weight (if that’s your goal).

    IOW: if you are slim, go ahead and enjoy a balanced intake of fruit; if you need to lose weight, limit your intake and give preference to lower-GI fruits like berries.

  8. says

    Keep in mind that modern fruit has often been bred for sweetness. And a fruit like apples isn’t even sweet (usually) when grown from seeds. Doesn’t that present a potential for increasing appetite and upsetting energy balance? But I don’t imagine that a bit of fruit now and then is a problem if it doesn’t lead to wanting more and more or produce other unwanted effects.

  9. says

    Chris,

    It’s never one thing, and that’s the problem with reductive science. Metabolism is flexible and adaptive, and in many ways, it seems completely lawless…it changes based on so many things—even in the course of a day. Unfortunately, unless we figure out some other effective language we are stuck with it, and hopefully enough common sense to figure things out.

    Your conclusions are correct, as I see it–nothing controversial about your recommendations–but the more important point, which I agree with, is not to demonize or rely on the ‘magic bullet’ because it really doesn’t exist. As I see it, fructose and sugar and flour and all the rest, are necessary preconditions (at least from my view from the bridge so to speak) but are probably not sufficient…

    It would be interesting to see though how many isocaloric diet include include a lot of HFCS, etc. and are really that healthy. But maybe…I guess you’d need to do the Twinkie diet for a year or even two not just a month?

  10. says

    Are there any problems eating fruit with or after a meal as oppose to as a snack/on its own. I can’t find anything definitive on this issue.

    • Jay M says

      IMO, it is best to eat fruits by themselves or least first. My first meal of the day is typically all fruits. My second and last meal of the day consists of fruits first and then some veggies.

      • says

        Yeah, I just like to see people touch all sides of the scenario. I totally respect Chris for going against the paleo grain here. I have much more respect for people that don’t cling to a certain mentality and don’t preach the same message over and over again without really taking the time to see the other side. There is another side.

        Even if you don’t agree with Ray Peat’s dietary ideas, you should surely appreciate his understanding of endocrinology and amazing depth of knowledge/philosophies; such as this quote right here:

        “Once we accept that knowledge is tentative, and that we are probably going to improve our knowledge in important ways when we learn more about the world, we are less likely to reject new information that conflicts with our present ideas. The attitude of expectancy will allow us to apply insights gained at one level of generality to other levels. No particular kind of knowledge will have such authority that it will automatically exclude certain possibilities in another field of knowledge.”

        • Martin says

          I agree Tyler,

          I have noticed recently that many in the Paleo community don’t seem keen to comment on Ray Peat as he does go against some established Paleo ideas (Fruit Sucrose as the main calorie source). When looking at the evidence he produces to back up this idea, coupled with the existing long-term established misconceptions promoted by the food industry/governments/pharma firms I think it would be very difficult to disprove what he promotes.

          I think it is likely that the well respected Paleo experts are keeping quiet at the moment until they can make sense of his work.

          It is very clear to me that Raymond Peat cannot be ignored or dismissed, his arguments and the plethora of evidence he uses to back them up are strong. I also like the way he puts things into context.

  11. says

    “The mice in the studies Lustig cites are eating huge amounts of fructose: up to 60 percent of total calories. You’d have to drink more than four 44 ounce Super Big Gulps a day to get that much fructose. Ain’t gonna happen.”

    Unless you’re a Ray Peat follower. Then, yeah, you might just have a problem… :)

    Thanks for adding some additional research to this issue, Chris!

    • John says

      Even Ray Peat followers would have a hard time getting fructose to be even 40 percent of their carbohydrate intake, let alone calories. Sure, Peat likes orange juice, sugar, and fruit, but all of those are 50-50 glucose and fructose. Ray also LOVES milk, and the lactose in milk contains no fructose. Agave Nectar (the only available food I know of that has a fructose percentage significantly higher than 50%) is not recommended by Peat.

  12. Austin Horn says

    Hey Chris,

    I’ve been a long time reader of yours (first time commenter); I’ve often wondered what your position is on Ray Peat’s ideas regarding the possible protective effects fructose? I’d be really interested to hear you thoughts. Thanks!

    Austin

  13. says

    The “forbidden apple” from the Garden of Eden, and concept of poison fruit seems to be debunked by you Chris! It never seemed logical to me that these delicious offerings from nature would be harmful- only in EXCESS, like most anything else in life, including water! Thank you for your measured approach to nutritional health!

    • says

      fructose is chemically more reactive than glucose. (If you know chemistry: it is inherently less reactive because ketose but exists much more in the open form). However, fructose is cleared from the circulation while glucose levels are maintained at a constant level. AGEs are due primarily to glycation by glucose, not fructose.

  14. Todd says

    Chris,

    I’m wondering what you think of Mat Lalonde’s opinion of fructose. Maybe he’s modified his position recently, but from what I recall he recommends limiting fruit consumption and total fructose consumption to no more than 50 g per day.

    See here for example (In the comment section of one of Robb Wolf’s podcast posts):
    http://robbwolf.com/2011/02/22/the-paleo-solution-episode-68/

    “As others have stated, fructose is limited in its usefulness to the body. Most of it is processed by the liver, kidneys, and fat cells. Glucose, on the other hand, can be used for fuel by any cell in your body. So you have the choice between fructose, a dose-dependent hepatoxin, and glucose. The choice is easy.

    The amount of fructose that can be tolerated depends on genetic variants as well as volume/type of training. Tolerated is the key word here meaning how much you can have without doing too much damage. If liver glycogen is completely full, than some fructose won’t hurt. In a sedentary population consuming a high-carbohydrate diet, some fructose does hurt. Observational studies have consistently shown that populations who consume more than 50 grams of fructose on a daily basis have problems with blood sugar control. The data is limited in its usefulness given its observational nature. Nevertheless, I like the 50g/day limit because it mirrors the limit for alcohol, which is also mostly processed by the liver. Now the limits don’t have to be identical since fructose and ethanol have different molecular weights but I still think it is better to try to keep fructose below 50g/day. Again, from a pragmatic standpoint, fructose is not a useful fuel and is potentially dangerous above a certain level. Why bother? And yes, you should minimize fructose from fruit. Some individuals seem to think that the vitamin C in fruit will some of the detrimental effects of excess fructose. Vitamin C does appear to have an effect on levels of uric acid (which was synthesized in response to fructose phosphorylation) but uric acid is merely one problematic aspect excess fructose consumption. Others seem to think that the fiber in fruit will prevent absorption of fructose.”

    • Nigel says

      While the scientific evidence of record may seem somewhat equivocal concerning the impact fructose consumption may have on achieving a desired low body fat level, the science which examines the insidious effect fructose imposes upon blood uric acid levels, is less equivocal.

      Fructose metabolism can deplete ATP, and this implies a temporary inability to synthesize protein and eventually the breaking down of the phosphates that make up ATP result in the generation of a few substances, including lactic acid and uric acid. In an article in the October 2007 issue of the “American Journal of Clinical Nutrition,” scientists report that this process may raise uric acid concentrations by 1 to 4 mg/dL after consuming a large fructose-based meal. Normal uric acid levels are between 3 and 7 mg/dL. Abnormally high results with uric acid can lead to a diagnosis of diabetes, gout, hypoparathyroidism, kidney failure, leukemia and host of other serious medical issues.- “Journal of the American Society of Nephrology;” The Effect of Fructose on Renal Biology and Disease; Richard J. Johnson, et al.; December 2010

      Mr Kresser intrepidly states that
      “Fruit has been part of the human diet for longer than we’ve been, er, human. We’re well-adapted to eating it, and capable of processing the fructose in it”

      It may be problematic to cast fruit as a commodity, whereas a vast qualitative difference may have prevailed between the fruit species our ancestors consumed throughout long-term evolution, versus the petrochemical produced hybrid varieties of fruit that are provided by our commercial markets today. Further, relative qualitative differences between fructose and other nutrient compositions of contemporary fruit may be significant.

      As middle-aged recreational triathletes, I and four of my peers, tested fruit as a primary source of carbohydrate fuel several times over two years. The results of these trials revealed that fueling on fruit was abysmally unsustainable and unsuccessful. Consuming whole natural fresh fruits (dragon fruit, durian, banana, etc) comprising 30% to 40% of daily total calories, lead to elevated uric acid levels and pain and discomfort that was in some cases physically debilitating. Ultimately it was not until we supplanted the major portion of our whole fruit-based carbohydrate source with processed white rice in quantities of 300 to 400 cal per day and maintained only a maximum of 50 g carbohydrate from whole fruit, that our athletic and active lifestyles became comfortable and sustainable.

      It may be helpful to note, that there is a pervasive feeling among us that attempting to employ fruit as our sole carbohydrate source, posed a barrier to achieving a lower healthy body fat level. Where a couple of us had some visceral type waistline fat to lose, it seemed the whole fruit was not conducive to calorie deficit fat reduction. This may be because fruit is relatively slow to metabolize and does not adequately prevent metabolic slowdown while calorie deficit dieting. We were only able to maintain acceptable metabolic rates and achieve our body fat reduction goals by adding small portions of white rice to our deficit diets.

      Clearly, Paleontology reveals that our ancestors did not evolve consuming cereal grains (processed white rice included), yet the pragmatic obstacles with attempting to fuel on fruit, which the physically active and/or athletic person may be confronted with today, can seem to leave no other viable option.

      Incidentally, Mr Kresser’s posting from some time ago, which revealed problems with a low or no carbohydrate diet – the problems being hormone (cortisol) imbalance, is particularly valid and helpful. Especially for us athletically active persons, our practical experience tests proved that lowering our carbohydrate component below a certain threshold, can lead to accumulation of excessive body fat, insomnia, and other health disorders

      Sincere thanks for for the helpful contributions on this important and seemingly enigmatic topic.

      • Paleophil says

        Hi Nigel, I appreciate your polite and constructive input. The report by Johnson, et al identifies the following as potentially problematic: added sugars, sucrose, high fructose corn syrup, sugar-sweetened drinks, fructose-rich drinks, and “the administration of 200 g of fructose per day.” Whereas regarding fruits, it says:

        “Forman et al. was unable to find an association of fructose intake with hypertension in studies based on nurses and health professionals. However, in these groups, a large amount of fructose was from natural fruits, which are known to be high in antioxidants and flavenols that can block the pro-hypertensive effects of fructose in animals; in addition, ascorbate also lowers uric acid by stimulating renal excretion.”

        So doesn’t the take-away appear to be to avoid adding table sugar to your foods, processed foods made with added sugars, and sugar-sweetened drinks–not necessarily to avoid fruits?

        • Nigel says

          Yes, theoretically whole fresh natural fruits should constitute a dietary virtue, yet in practical terms it seems athletes, especially athletes aiming to reduce body fat need adopt alternative sources of carbohydrate to fruit. At first I did not want to believe the thesis of the Paleo Diet for Athletes (essentially that endurance athletes need concentrated glucose that is rapidly metabolized and need diverge from a standard Paleo diet), but our practical trials have corroborated the validity of the principles presented. Likely healthy non physically active or modestly physically active persons could sustain adequately with fruit as the only carb. source.

      • says

        Thanks for this great contribution Nigel, I for one appreciate you presenting your real world experiments and results.

        I don’t find it in the least bit surprising that you weren’t able to fuel yourself effectively with high levels of fruit, I found the same thing when doing the Yorkshire Dales 3 peaks a few months ago (I wrote up my experiences for a friends blog here: http://foodandfitness.co.uk/homemade-food-hills/#more-3255).

        Thanks again,
        George

    • says

      fructose is interconvertible with glucose (that’s why the GI of fructose is 20, not 0) and although initial pathways are separate, metabolism converges at the level of the triose-phosphates (three carbon compounds from the lysis step in glycolysis). The major problem with fructophobia is that it impedes trying to find out how fructose and glucose are really different. The attack on fructose is similar to the attack on fat which has produced, as they say, much heat, but not so much light.

      • Paleophil says

        Well said, Dr. Feinman. One oversimplification (demonization of saturated fat) has largely been replaced in the LC and Paleo spheres by another (demonization of anything containing significant fructose or glucose, especially fructose). Thanks for being a voice in the wilderness on this.

  15. Alex Krohn says

    I totally agree! Lustig demonized fructose and made alot of people in the paleosphere scared of fruit and more accepting of high glucose foods like sweet potatoes. Plus there is a less dramatic insulin response with high fructose foods like an orange compared to high glucose foods like bananas. What are your thoughts on the increased likelihood of fructose turning into AGEs?

  16. says

    Interesting stuff, but I wonder to the degree we’re not taking into account behavioral/psychological aspects of this argument. Biology may, in the end, trump all, but behavioral patterns can influence biology. Their interaction suggests they may be on an equal playing field. I agree that in an isocaloric state we might be fine, but in calorie excess things might go awry. Can’t we easily achieve a hypercaloric state through the consumption of fructose heavy fruite? Especially given research suggesting that fructose results in less physiological reward than expected and may lead to overconsumption (Volkow et al.). In the lab I work I don’t see many of the kids or adults compensate for the excess fruit consumed by down-regulating consumption. Especially if the fiber content is low and perceived sweetness is high. I’m not trying to debunk the main point that fructose has not been proved to be uniquely fattening and that fruit should not be avoided, but wouldn’t it still be prudent to limit certain fruit types and quantity when trying to lose weight? Thoughts?

  17. Eric says

    Chris,

    What fruits do you recommend in terms of overall health and longevity? I have heard that many fruits today have been bred to be large and very sweet, but this doesn’t necessarily mean nutrient dense. I tend to go with things like cranberries, wild blueberries, goji berries, raspberries, pink guava, and dragonfruit.

    Thanks,

    Eric

    • Jay M says

      My diet consists of mostly fruit and some veggies. In order to get enough calories and maintain weight, I tend to rely on the fruits that have more sugar (bananas, mango, papayas) not less (berries).

  18. Evan says

    Great post, Chris! It is refreshing to see these distinctions (real vs processed food, animal vs human). All too often I think that people are quick to draw conclusions without regard to context.

  19. tess says

    i’m appalled that the “ancestral health” community is embracing sugar to the extent it is. sugar has so many downsides, …where is this coming from??? and differentiating between fruit, corn syrup and sucrose-sweetened treats is rather ridiculous in this era of bred-for-sweetness fruits. in a banana there are about 45g of non-fiber carbs — that’s equal to about a quarter-cup of sucrose, with a comparable breakdown of glucose to fructose.

    furthermore, fruit is a traditional tool to encourage appetite. add to this the fact that a lot of people have fructose-absorption issues. i think it’s irresponsible to recommend fruit to people who need to lose weight, especially as a between-meal snack!

    • says

      I eat 4-5 servings of fruit a day, and I’ve lost 60 pounds. Thanks for telling me how I’m doing it all wrong! From BMI = 34 to currently 26. That last 10 pounds is tough, I’ll have to try to eat more fruit!

      And how’s your diet going?

      • christy fike says

        Julie just curious what else you are eating/what kind of exercise are you doing to have lost those 60 pounds?

        • says

          i don’t have too many hard/fast rules. I’m not paleo – eat lots of beans, a bit of meat, a bit of whole grains, too much dairy, lots of fruits/veggies, coffee with regular white sugar. I rarely eat out, and I try my best to eat only when hungry, and not stuff myself, nor eat huge portions. If I eat a big late lunch, I may just have fruit or salad for dinner, I no longer force myself to eat just because it’s mealtime, or anything but hunger. I go to the gym a few days/week, cardio, strength training, yoga, and I do about 80% of my transportation by bike or walking. It’s slow but steady, what tends to screw me up is alcohol and restaurant food (big heavy portions). And my co-workers candy bowl, which i finally had to nix altogether, hardly like the stuff yet I couldn’t keep it to just one stupid way-too-sweet mini Reeses Cup, started eating up to three daily, so now I don’t even start.

    • jane says

      Honestly, this isn’t about fruit – it’s about fructose. There’s a difference. Lustig says that fruit in moderation is OK because it has all its fiber. We’re talking about the copious amounts of HFCS that is in processed food – including juice.

      • sandy says

        Exactly, Jane. I believe that if fruit was the only source of fructose than there probably wouldn’t be any cravings for junk food. My mom says, “Fruit is food, vegetables are medicine.” Of course, I can’t resist to add that proteins and fats are essential.

      • Chris Kresser says

        But that’s what I take issue with. The comment that fruit is only okay because of the fiber implies that the fructose it contains is harmful, but the fiber somehow cancels that out. But the research I pointed to in this article shows that fructose is not a problem unless calories are in excess.

        • says

          One thing I would have liked to see you present, Chris, was what feedback you have from your clients in relation to the fruit issue?

          I personally have to be pretty careful with fruit, as it can work out as an ‘avalanche’ food for me. Once I get started, i can find it hard to stop…

          This is especially the case with chopped fruit salad, but much less the case with whole fruit eaten one at a time, and don’t even get me started on dried fruit!

          I appreciate your thoughts,
          George

          • Paleophil says

            I also have a history of bad problems from fruits, but I found that there are dramatic differences in effects between various fruits. I’d be curious to learn which specific fruits affected you badly, George. Thanks.

            • says

              Hi paleophil,

              Right now, I’m not totally sure about the finer details, as this is pretty new to me.

              It’s only since going totally paleo (2 weeks) that I’ve noticed it. But…

              It seems that the higher the sugar content, the greater the avalanche. So dried fruit comes tops, then things like mango, with berries coming last, but not really by much.

              I suspect that some part of it that I’m still going through a sort of mental detox and in the process of learning new eating habits; using fruit to try and capture some of the experience I got with grains, probably. I’ll know more when my eating is more under control and I get a sort of background reading of my psyho-emotional state that allows me to more closely appreciate the varying effects of different fruits.

              Hope this helps,
              George

              • Paleophil says

                Thanks George, that’s pretty well in line with my experience, except I find that certain berries and fruits (wild Maine blueberries–fresh in season and frozen ones year-round are available locally–wild black and red raspberries, wild and organic blackberries, wild river grapes, lemons, limes and certain other fruits) seem to be substantially less of a problem for me than dried fruits, mango, bananas, oranges, pineapple, papaya, green grapes, pears, and apples.

                Dried fruits seem to be the biggest offenders for me, possibly due to the concentrated sugars and the tendency to eat way more calories and grams of sugar at a sitting when eating dried than fresh fruit, and who knows, maybe even the heating of the fruits by commercial dehydrators at who-knows-what temperature. I don’t think the sulfur dioxide in the preserved dried fruits affects me significantly, though I’m not certain. Interestingly, the cheapest, most commonly served fruits all seem to give me problems. I wonder how many people judge all fruits based on them?

                I do think that my carb tolerance has improved some during the last couple years, but I’m still far less carb-tolerant than average. I’ve been doing a Paleo/ancestral-type diet since 2004.

                Good luck,
                Phil

                • Jay M says

                  Fresh fruits are packed with water which expands the stomach and limits the quantity ingested.

        • Storm says

          Everything in moderation even that which is nutrient dense and whole foods.
          If you eat a bag of lollies you are going to have issues, if you eat a whole case of mangoes you are going to have issues.

          Chris
          What I take from this is exactly what you said that fructose becomes a problem when calorie intake is too high.
          In short if people are overeating irrespective of what eating style you have, Paleo, Zone, Vegan, Vegetarian, Raw food your calories will be more than the energy you are expending and you will put on weight. Obviously this is subjective to lots of variables but overeating is still overeating.

    • Michael says

      An average banana has about 30g of sugar, if I’m not mistaken… And this meme about modern fruit being bred for sugar; weren’t there plenty of fruits in ‘paleo’ times with sugar in them too? Of course, they wouldn’t be avaiable year round, but that’s not what we’re talking about here…

      As for the ‘irreosnibsility’ of this article- isn’t it clearly stated that this recommendation isn’t for anyone with glucose toelrance issues etc…

      • jake3_14 says

        Outside of the tropical zone, humanity had little opportunity to eat fruit, except, as you note, seasonally (summer to early fall). Those fruits, tropical ones excepted, though, were not very sweet. Apples, in particular, were somewhere between bitter and tart.

        But those tropical exceptions do raise an interesting question: how much of them did Neanderthals and early modern humans eat?

  20. Jennifer R says

    Shouldn’t there be a mention of eating locally and in season in the article? Vitamin D is important in processing sugar so February in Seattle probably isn’t optimal for eating a bunch of sugar regardless of its form.

    • Heidi says

      Eating locally is good for the earth,the economy and probably for the nutritional value of the food, but it doesn’t make sense to avoid some food(s) because they are out of season. Up north where I am, we’d be subsisting on snow for 6 months of the year. My recent ancestors are from Europe in a place where it’s much warmer, so what is available there is a much different diet than what I can grow here. But where did they come from? Humans can adapt to eating a lot of different foods. Thank goodness someone had the good sense to introduce sushi in Canada :-)

  21. says

    Enjoyed the post, Chris. Always appreciate your balanced and reasoned approach. Any plans to do a post comparing natural fructose to high fructose corn syrup?

  22. Sarah says

    How about raw honey? I removed all cane sugar and now bake with raw honey….good idea, bad idea, limits on how much I should feed my family??

  23. zack says

    I recall Lustig saying that the fiber in fruit and vegetables was enough to counteract the fructose contained within. The same couldn’t be said about juice. But that doesn’t mean people tuned that part out either.

  24. says

    Chris! Hello, my friend. Any thoughts on the Ray Peat/Josh Rubin take on Fructose and sugar in general? Ray emphasizes the importance of sugar intake, specifically as it relates to its role in combatting the stress response. Their take on gluconeogenesis makes sense to me, and more and more of my former “Paleo” friends are now drinking OJ daily…

    • Jay M says

      IMO, a diet high in fruits should be relatively low in fat & proteins. A diet high in fats & proteins should be relatively low in sugars of any type including from fruit.

  25. Florent Berthet says

    What about the claim that when the glycogen stores of the liver are full, excess fructose is converted to triglycerides? Would that be a reason to eat your fruits BEFORE your other carbs during a meal.

    • Jon says

      It would only matter temporarily, which isn’t clinically relevant. At the end of the day, it’s energy in versus energy out. Our body is constantly storing and burning fat.

  26. David says

    I’m not sure what to think about this,
    the conclusion of this Blogpost, as I understand it, is that a glas of Juice and some Fruit is okay and good for us. As someone who recently found to paleo I totally agree with that but I don’t see that Lustig nor the paleo-community said otherwise, as I understood it. Lustigs scientific evidence may be lacking, but his general statement that HFCS and sucrose is the huge problem is absolutely correct IMO.

    • says

      You can’t combat terrible science with not-so-terrible science. Lustig is incorrect in stating “fructose is as bad alcohol” and has no evidence to prove it. Everyone states that HFCS is bad – for the most part – so I rather someone who’s honest and factually correct be at the forefront of the natural foods movement. My main grievance with Lustig, is his want to legislate against HFCS. Prohabition is not only idiotic, but immoral.

      • DancinPete says

        I’m totally against prohibition, but I think that removing the tax subsidies for corn farmers would be a start in the right direction. Why are out tax dollars spent to enable farmers to grow HFCS, and then we turn around and try to tax the end result to convince kids not to drink soda? It seems the only ones who benefit from this are the gov’t bureaucracies.

      • helene says

        We are paying for idiots who ingest hfcs and dose it out to their offspring. We support these ppl thru legislated robbery of our paychecks to fund social services. If the kids are born into a solvent family then when they are disabled due to their stupid lifestyle choices and go on SSI and Medicaid, Medicare etc, we pick up the tab, then if not before.
        If the govt can legislate theft of my paycheck, then it can legislate poison as illegal.

  27. says

    Another excellent well balanced article.

    For those that live in the UK that missed the first of the series “The Men Who Made Us Fat” might like to try the BBC I-player here http://www.bbc.co.uk/iplayer/episode/b01jxzv8/The_Men_Who_Made_Us_Fat_Episode_1/ I’m not sure if this is available outside the uk but it features the whole diet problem since Ancel keys and his flawed research that he manipulated to confirm his own theory that fat made you fat. It show the problems caused if you assume all calories are the same. Tests in a laboratoy only show that the test works in a laboratory (in vitro).

    My mother spent her life eating ‘low fat’, low sugar, high fibre, ‘healthy’ weight loss food with loads of bran. The last thing any of it ever did was help her loose weight. One of her favorite foods she had given up was sweet corn because it was high in calories. We now know that just because food tested in a laboratory contains x amount of calories, doesn’t mean they’re all available to our digestive system (bioavailable).

    My mother’s ‘healthy’ low fat, high fibre, artificially sweetened diet gave her type 2 diabetes and bowel cancer and her weight didn’t go down till the cancer resulted in half her intestines being removed. Not the best way to loose weight!

    The above program does focus on high fructose corn syrup and includs interviews with Lustig and other names familiar with visitors to this site and Drs. Mercola and Briffa. The Weston A Price Foundation and George Monbiot even get a mention. As the first of 3 we’re eagerly awaiting the next two.

    I understand that sugar IS the casue of all diet problems but that fructose is by far the most damaging of the two types. What people seem to forget is that you don’t have to consume sugar to actually end up with two much in your body. Whether pure carbohydrate like sugar or grains in the form of bread or pasta etc, the body turn these into sugar as well. So while cutting down on sugar is a no brainer, subsituting it for artificial sweeteners or forgetting about those grains make it a pointless excercise.

    • says

      “I understand that sugar IS the casue of all diet problems ..” Where did you come to this conclusion? It is definitely not “thee” cause to all diet problems. What about PUFAs, intestinal irritants, nutrient deficient processed foods, etc.

    • Cristiano K says

      Well, thanks for the info. So sugar is the master evil, the root of all diet problems. I always suspected that. My new super healthy diet will consist of hydrogenated soy bean oil, wheat protein and to top it off, grain fiber. I’m sure i’ll loose weight, since it’s a zero carb diet, you know, theres no evil sugars or evil starches.

      • says

        OK You got me there. Poor choice of words. I still believe its the worst culprit because its in all processed foods, including savoury food. By default the body converts carbs into sugar that you haven’t even taken. I didn’t go down the hydrogenated fat, soy bean oil route because I’m sure most visitors to this site know the dangers of these. Wheat is only 6% protein so not sure if you mean the whole grain or an extract. If you mean the whole grain you’re back on carbohydrates in your fictional diet.

        • Martin says

          No, I think you will find sucrose in processed foods is the least of your worries. Its all of the other rubbish in it that causes big problems.

    • Jay M says

      “I understand that sugar IS the cause of all diet problems”. I guess someone forgot to tell the long-lived Okinawans whose diet was 85% carb (mostly from sweet potatoes).

      • jake3_14 says

        The Okinawans are genetic freaks who have traditionally lived in isolation from the rest of Japan. Studies have shown that their genetics help them in preventing inflammatory and autoimmune diseases. In addition, the carbohydrates in Japanese sweet potatoes (which are botanically in the yam family) are higher in amylopectin, which slows the rate of digestion. In addition, traditional Okinawans simply eat fewer calories than the average person due to a cultural practice of eating until you are only 80 percent full called Hara Hachi Bu. Moreover, when Okinawan leave their isolated villages, they adopt all sorts of modern habits, and they shorten their lifespans.

        In short, Okinawans are outliers and not relevant to the rest of us.

  28. Waldo says

    Chris, This is technically a great article and I wouldn’t doubt your research. Yet there are other important aspects of fructose you didn’t speak to that Dr. Lustig does. I really wish you would have prefaced this article a little better in that regard. Dr. Lustig has always pointed out fructose is poison to metabolically broken people, leptin resistant mainly. You could have brought up the fact that fructose is addictive and lights up the reward centers in the brain. Eating/drinking doses that are not in natures packaging (even a small glass of juice) could cause cravings that lead to the over consumption of calories that sets bad cycles in motion. The poison is in the dose, if addicted then a little gets to be more and more then you’re metabolically broken. That’s Dr. Lustig’s stance. Can an alcoholic have just one drink, sure but its likely to awaken their demons. As he says, “sugar is the alcohol without the buzz”. That’s a risk that should have been prefaced.

    • helene says

      Ah there is a buzz. You better believe it!! Someone in the throes of a sugar fest, several times a day occurrence waaaaaaay more often than researchers would like to admit, is exactly as a drunken man. Out of control and loving every drugged minute of it. With self hatred and remorse afterwards…whilst on their way to find their next drink/candybar/Starbucks.

  29. says

    I appreciate the balance that I’ve been seeing from you, Robb Wolf, the Hartwigs, etc. The hardline stance of Lustig, especially when he started talking legislation/regulation of fructose was over-the-top. That said, when Lustig talked about the metabolization of fructose in the liver resulting in uric acid production at the 58 minute mark of The Bitter Truth lecture, a lightbulb went off for me. As a gout sufferer for decades, I immediately eliminated added sugar from my diet with the idea that if I had an overproduction issue with uric acid, I should be able to resolve that issue by removing the likely source of the overproduction. I was able to stop taking allopurinol and haven’t had a gout attack since. A few months later, I went full paleo and felt even better, but the elimination of added sugar (I still ate whole fruit), took care of gout for me, so kudos to Lustig for at least getting my attention to try something. It could be a different mechanism entirely that led to a gout cure, but I’m sticking with the idea that fructose/sugar in general appeared to be a bad idea for me.

    • Chris Kresser says

      The research on fructose, uric acid and gout is mixed. I plan on covering this in a future article.

    • Jay M says

      Fruit consumption is not the root cause of gout, but supplying extra fuel, esp glucose/pufas, to an immune system that is already at defcon 5 is not good. However, it is better to eliminate the things that are triggering the immune system. In my experience, the foods that trigger the immune system the least are fruits and veggies. Some of the worst offenders are dairy, processed foods and animal products.

  30. Mike T says

    My take away from Lustig lectures and articles is that chronic fructose intake is dangerous for people who are glycogen repelete, which describes the majority of the population. I can’t comment on the science on way or the other as I don’t have the background in biochemistry, but the most persuasive part of Lustig’s take on fructose is his clinical experience. What often seem to find is we have academic research that may be “correct”, but has little relevance in clinical environments because of the confounding factors that clinicians often run up against. Can the average paleo follower tolerate the occasional dose? Probably, as they are most likely to be relatively healthy and are managing many of the other risk factors which could lead to fructose “toxicity”.

    On the other hand, talk of prohibition etc. is ludicrous, Just when the public seems to become aware of the terrible problems associated with all types of prohibition, to be calling on to add to damage it does to society is dangerous. When sugar is outlawed, only criminals will consume sugar.

  31. Waldo says

    The more I think about this post the more I see the data is based on acute responses but this is a chronic problem. That’s what Dr. Lustig argues. There is no risk if there is no exposure. Fructose as well as wheat are ubiquitous (major exposure, major risk) to our society.

    • Chris Kresser says

      This post is based on information from Stephan’s article, which I referenced, as well as an article by Evelyn at CarbSane, which I also referenced. They’re both excellent sources for this kind of information.

      • Paleophil says

        Oops, sorry for the redundancy. Guess I read too fast and either missed or forgot the reference to Stephan’s article.

        • Paleophil says

          I’ll try to make up for that faux pas by adding that for those interested in more info on fruits, Denise Minger, Chris Masterjohn, Staffan Lindeberg, MD PhD and Katharine Milton, PhD, are also good sources of info on the topic. For example, Dr. Lindeberg reported in Food and Western Disease: Health and Nutrition from an Evolutionary Perspective on p. 51 that wild fruits tend to contain a HIGHER, rather than lower, ratio of fructose:

          “Fruits, which have likely been consumed in large quantities by our primate ancestors, differ from other edible plants in that they contain appreciable amounts of fructose, a monosaccharide, which typically constitutes 20-40% of available carbohydrates in wild fruits (456, 932, 1226) and 10-30% in cultivated fruits (1275). A daily fructose intake below 60 g, which is considered to be safe, corresponds to 4-5 kg of pineapples (1568, 1857). Approximately two-thirds of dietary fructose in the US population is provided by non-natural foods and additives, mainly sucrose and high fructose corn syrup (1390).

          Dr. Milton pointed to higher levels of sucrose in cultivated vs. wild fruits: “One important difference between wild and cultivated fruits is that sugar in the pulp of wild fruits tends to be hexose-dominated (some fructose and considerable glucose; Table I) while that of cultivated fruits tends to be highest in sucrose, a disaccharide.” (Milton, Katherine, PhD, 1999. Nutritional characteristics of wild primate foods: do the diets of our closest living relatives have lessons for us? Nutrition, 15(6): p. 490, http://nature.berkeley.edu/miltonlab/pdfs/nutritionalchar.pdf.)

          So there are multiple possible reasons for why wild and heritage varieties fruits aren’t as bad as table sugar, HFCS, sugar-sweetened beverages and such, and the all “fructose” = poison meme does seem to be an oversimplification.

  32. Terry says

    I am so glad to read this. I have been paleo for a little over a month and I do not use any type of sugar at all. I have used honey on maybe one or 2 occasions, and maple syrup once. So it is not a big problem for me, however, I am a fruit fiend. I have cut way back and mostly use raspberries, strawberries and blueberries, and since it is now in season cantaloupe which are all on the lower sugar side. I had someone tell me, sugar is sugar is sugar, whether it is fruit, table sugar, agave or anything else. I have been feeling guilty about my fruit, but I wont any more. Love your info by the way. I follow you on FB and email. I appreciate you putting out free information for my health!

  33. Chris Drozier says

    Hi Kris
    I read your view on Fructose.
    How do you explain Dr Lustig’s statement that the only teens that fail in the clinic program (UCSF?) are those who won’t stop drinking sodas?
    Thanks. Chris

    • Chris Kresser says

      Because frequent consumption of sodas will tend to cause overconsumption of calories, and in excess energy states fructose has harmful metabolic effects. I completely agree with Lustig on that score. The purpose of this article was to point out that fructose (and sugar in general) does not appear to have those harmful metabolic effects unless calories are in excess.

      I don’t recommend people drink fructose-sweetened sodas, period. But fructose in whole fruit – barring fructose-intolerance, a digestive issue or Type 2 Diabetes – does not cause metabolic harm for most people.

        • paleophil says

          Excellent point, High Fat Hep C Diet. Nonperishable sealed soda pops, soda vending machines and such make frequently snacking on high-calorie sugary beverages between meals easy.

        • helene says

          Yes, just becuz an infant can being sucking breast milk whenever it needs to suck…if one does give manmade bottles of water/juice and pacifiers…does not mean older children, or adults, for heaven’s sake, can be constantly ingesting calories! Our bodies don’t do well thus treated. A baby’s thrives. We can’t always cross over conclusions without using logic along the way.

  34. Louise says

    Thanks for that Chris, I am getting so confused these days, I totally get the sugar/HFCS part, but was starting to wonder about fruit because of the fructose, it did not seem right to take that out of the diet too. sugar out, fruit stays.

    • Jay M says

      Plants have been producing fruits for millions of years because it is mutually beneficial. No need to be cautious of fruits, it is other 90% of the stuff in grocery store.

  35. Paleophil says

    Chris explained the effect of soda pop in his post thusly: “When people add a soda or two a day to their diet, they tend not to reduce consumption of other foods, and thus their calorie intake increases.

    This is where fructose does appear to be more harmful than glucose. Although people don’t compensate for calories added via glucose or fructose, the fructose-sweetened beverages have more serious metabolic effects.”

    Chris didn’t advocate for drinking soda pop, but imagery tends to be more powerful than words, and thus Waldo has a point about the soda image. It’s attention-grabbing, but may be misleading some folks. Perhaps a picture of fruit would have been better?

  36. says

    A similar discussion on this 25 year old Swedish research is taking place on the shape.com website. All the comments are similarly critical of the research. The most succinct comment being this one from Brigitte :-
    “The body’s preferred fuel is fat, whether it’s from the diet or used from our stored fat.. the body uses up sugars first only because it must, as sugar is dangerous. You cannot use your stored fat for fuel when insulin is present……if you eat carbs all day (all carbs=sugar even whole grains,) you keep insulin present all day and your body cannot access your fat for fuel so it has no choice but to tell your body to eat to get the energy it needs. That is why you are ALWAYS hungry when you eat carbs. When you switch to low carb, this process corrects itself and you go many hours being satisfied, all the while burning those love handles for fuel instead of eating…seems like magic but it’s simply biology. Low carb paleo changed my life, it can change yours too.”

    • Dennis says

      And your point is …?
      If the body’s preferred fuel is fat as you state, why then if we eat only protein and fat will our body convert preferentially fat into glucose for fuel ?.. and if fat is used up then the body will tear down the body structure for fuel ,i.e body tissue/ proteins.This does not sound very desirable. Indeed it sounds quite a stress.

      The simplification that ‘all carbs = sugar’ forgets to make mention of the magnesium/potassium and other minerals & vitamins ,etc which come with ,and help us to use, the sugar

  37. Chris Drozier says

    Adrian I’ve read this before…
    Yet I used to eat 1.5 lb or whole wheat sprouted bread per DAY!
    I never gained much weight although I did not and still don’t exercise.. (not good I know).
    I am now 61, I eat about 1/3 lb of same bread, I am about 5 lbs heavier than I was at 25:
    I am now 5’8″, 142# and consider myself thin although the bread gave me a bit of a beer belly.
    I am quite versed in Nutrition and can’t explain how I ever ate 1.5Lb of that bread daily and never gained a pound.
    Also, I am skipping midday meal these days (not good but not hungry) 3-toasts loaded w butter keep me going all day! Only sprouted whole grain brad does that — the white stuff and I am hungry within 4 hours at most.
    WE ARE DIFFERENT!
    I never drink sodas and cut my water with 1/4 to 1/3 juice + stevia sometimes

  38. Jasmine says

    I find it interesting that fructose is labelled ‘as bad as alcohol’ yet we are often told that drinking a glass of red wine each day can be beneficial.
    I think after everything is considered, balance and moderation is the only approach to take. Too much of anything is never a good idea.

  39. Mark says

    There is something uniquely bad about fructose. Look up the fructose fed rat model, a standard tool for studying insulin resistance and hypertension. It only takes two weeks on a high fructose diet to get rats to develop metabolic syndrome. As the months go by, evidence linking the metabolism of fructose in the liver
    with the development of fat accumulation, insulin resistance, hypertension, and altered immune function accumulate. A quick search of PubMed is all that is required to see how the pieces are starting to fit together. Of course it doesn’t matter how you get the fructose, whether it is from excess sucrose or from high fructose corn syrup.

    • Chris Kresser says

      Did you read this article? The whole point is that you can’t extrapolate rat study results to humans, because rats metabolize carbohydrates (including fructose) differently than humans. I also pointed out that the amounts of fructose given to the rats is much, much higher than what humans eat.

  40. says

    Great article Chris,
    I think people take a lot of information out of context when it comes to nutrition.
    My experiences say moderate, thin skinned dark fruit consumption has never harmed anyone with healthy body composition. However, overweight and obese clients have almost universally done better abstaining from all fruit for the first 2-4 weeks.
    That said, I’ve found it to be the higher mass and carb fruits (bananas, pinapples, etc.) that most people need to watch. Especially if adding them to an already carbohydrate dominant diet.
    Excellent information as always, many thanks,
    Jeremy

  41. says

    Most cancer is fed by glucose and uses copious amounts of it. Has there been any research as to the metabolism of fructose by neoplasms?

  42. Ulrik says

    Thank you for your thoughtful analysis, as always, Chris!

    I have a question tangentially related to this, which has been bugging me for a while, and I hope you might take it up sometime (or refer me if it’s covered somewhere): How exactly are hypo/iso/hyper-caloric diets defined? At first, it seems like a trifle: just compare with basal metabolic rate + activity level.

    But on the other hand, the goal of wellness care is to optimize well-being, and this includes a feeling of “having lots of energy”. We all know that some diets cause us to be lethargic and ill-feeling, whereas other diets do the opposite, even with the same amount of calories. (Of course the environment generally play a role as well: stress/emotions/sunshine, etc.)

    It seems intuitive that a “hyper-caloric diet” that makes you feel really good and energetic is much healthier than a lower-calorie diet that makes you feel lethargic and ill, and possibly makes you fatter as well. How do diet researchers deal with this issue?

  43. Jennifer D says

    If fructose is not the cause, why has there been such an increase in the incidence of non-alcoholic fatty liver disease? Is it just excess calories in general?

    • Waldo says

      Fructose is the cause if you live a hyper-caloric diet. An unintended result of Lustig’s, “Sugar The Bitter Truth” is the Fructose-Phobia in the Paleo community. That’s the point. This is a hard article to navigate the first time through. Just because most of us here are recovering metabolic-aholics. Chris actually did a nice job explaining that if your metabolically healthy — enjoy your fruit. If you have metabolic issues — stay away. And he never, ever advocated the consumption of sweetened beverages (besides a small glass of juice). The best article summing up sugar (especially fructose) is Gary Taubes’ New York Times, “Is Sugar Toxic” which is heavy on the Dr. Robert Lustig references. That is fantastic, but you may not need to go there if you re-read Chris’ article and get the context. Hyper-caloric diets rich in sugar laden foods indeed causes Non-alcoholic fatty liver disease. If your Paleo template is in order, your should be okay. I feel if you eat alot of fructose you are actually twice as doomed. First as Chris points out your metabolism does account for fructose calories, and second fructose sweetness is addictive in high quantities. So you’ll want more food, and the more food you’ll want will be sweet carbs.

  44. ChrisG says

    My problem with fruit is that I frequently binge on it, despite the claim that this should be unlikely. If I buy blueberries in season the pint frequently disappears… during the drive home. Good apples or navel oranges…I can easily eat half a dozen during a single day. I don’t do this with sweet potatoes. Getting my carbs right is very important, but fruit for me is generally a bad choice because of the binge-factor.

  45. george henderson says

    fructose only causes problems in caloric excess? But if you’re eating sugar/ HCFS in caloric deficit these might be replacing foods that supply more elements of nutrition (it’s hard to think of foods that supply less). I believe sugar causes tooth decay whether one eats too few or too many calories. Metabolic syndrome and type 2 diabetes hit some people of normal weight who consume fructose/sugar.
    I suggest analysing the Lustig hypothesis in its published form, as it has aspects (such as Fox01 activation) that are left out of the video presentation.
    http://podcast.uctv.tv/webdocuments/Fructose-and-Ethanol.pdf

    I think it is worth asking whether Lustig has dumbed down the evidence for public consumption, and whether it behoves us to make a better job of interpreting it before we dismiss it altogether.
    If there are holes in it (and Peter at hyperlipid has pointed out that Glut5 is far from exclusively hepatic in location), I think it’s worth trying to patch them and see if the thing still floats.
    If you think PUFA is also to blame, for example, what happens when you add PUFA to the Lustig hypothesis?
    It definitely seems to belong in this one: http://www.nature.com/nrgastro/journal/v7/n5/authors/nrgastro.2010.41.html

    Before dismissing this idea out-of-hand, why not try to, in the immortal words of Tim Gunn, “make it work”?

    • Chris Kresser says

      Sugar is certainly not optimal as a major source of calories, whether overall calorie intake is in excess or not. I don’t think anyone would make that argument. The point was that the evidence doesn’t support the notion of sugar being “toxic” or contributing to significant metabolic problems in isocaloric diets.

      • George Henderson says

        Here’s an interesting question; if someone has elevated blood glucose due to overactive gluconeogenesis or insulin resistance, does this mean that any fructose they eat is processed as if they are in a hypercaloric state?

  46. george henderson says

    You can look at healthy volunteers, and isocaloric states, for relatively short time periods, and conclude that fructose (or the fructose-glucose combo) is not problematic. And you can feed unhealthy volunteers the same thing, and see problems. The experiment that takes healthy people and makes them diabetic in a prolonged, controlled experiment, over decades to match the natural progression, is probably impossibly unethical (and the controls might well be on the same path).
    There are perhaps two ways in which fructose might drive this 1) through the hedonic pathways Lustig describes (sugar, like alcohol, is a subversively moreish influence to many of us) leading to the “fructose & isocaloric” state.
    2) through sugar lending itself to “snacking” – constant caloric intake disrupting traditional feeding schedules. It does this through the its role as a preservative, flavouring, and appetite stimulant. To understand how this might contribute to diabesity, try the thought-experiment of reverse engineering the various experiments in intermittent fasting, or time-restricted feeding: http://www.salk.edu/news/pressrelease_details.php?press_id=560

    If these two behavioural effects of sugar tend to create the sustained hypercaloric environment in which sugar, and perhaps other elements of the diet, contribute to metabolic problems, might that qualify as toxicity?
    It is a feature of the Lustig hypothesis, in its published form, that it involves multiple discrete effects of fructose, and the links between them are not in every case drawn with the sort of detail that will be available in future, or that can perhaps be supplied from informed speculation. There are a lot of implications that haven’t been tested. There are probably implications in there that haven’t been realised yet.

  47. George Henderson says

    Going back to the Guyenet discussion, I don’t think that the researchers he quotes actually went through the Lustig references; it looks like they did their own search. And I question this statement: “in each case there was no effect of fructose when it was isocalorically exchanged.”
    Many studies have been done where sugar is isocalorically exchanged with various foods, for example the comparisons with honey (a very similar food) linked to Mark Sisson’s blog recently: http://www.marksdailyapple.com/is-honey-a-safer-sweetener/
    for example, http://www.ncbi.nlm.nih.gov/pubmed/15117561
    (which also distinguishes between dextrose and sucrose, which do NOT seem to have identical effects).
    If there are differences between honey and sucrose, isocalorically exchanged, then there are going to be differences between say, sucrose and starch. Whether these amount to much is another story, but I think the claim that there is no effect needs to treated with scepticism.
    Also I question whether the subjects in (say) the honey experiment above were carefully fed beforehand to optimise calories, so that the extra sugars were hypercaloric. This doesn’t appear in the abstract, and strikes me as an unusual proceeding.
    I am not saying that the honey research proves anything re: Lustig, except that the “isocaloric” claim may be misleading. Guyenet does refer to Sisson’s honey link in his summing up. One can defend the intake of sugars from whole fruits and honey, in a hunter-gatherer “intermittent fasting” milieu, as healthy without extending that definition to include sugar, HCFS, apple juice concentrate and agave nectar.

    • says

      “(which also distinguishes between dextrose and sucrose, which do NOT seem to have identical effects).”

      They do not have the same effect because they are not the same thing. Dextrose (a simple sugar also known as glucose) is a monosaccheride while sucrose (more commonly known as table sugar) is a disaccharide of both dextrose and fructose. Honey however is a very complex substance that also contains both glucose and fructose that would have the same effect wherever they were found. The benefits of honey come from everything else it contains that is neither glucose or fructose. Probably repeatiing something already on this very long.string.

  48. Paleophil says

    George Henderson wrote: “One can defend the intake of sugars from whole fruits and honey, in a hunter-gatherer “intermittent fasting” milieu, as healthy without extending that definition to include sugar, HCFS, apple juice concentrate and agave nectar.”

    I haven’t seen Stephan or Chris extend the definition of “healthy” to “sugar, HCFS, apple juice concentrate and agave nectar.” Quite the contrary, my recollection is that they have warned against eating those sorts of foods and extolled the virtues of natural whole foods. Chris even referred to “sugar (especially high-fructose corn syrup)” as a “dietary toxin” here: http://chriskresser.com/9-steps-to-perfect-health-1-dont-eat-toxins. Perhaps he might word that a bit differently today, but it shows that his history on this topic is not one of promoting added sugars.

  49. george henderson says

    @ adrian, exactly, which is why claims that fructose “has no effect” must be carefully weighed. This is clearly a personal interpretation of data that others might interpret differently.

    @Paleophil, I agree, but Chris is here providing a link, through Stephan Guyenet, to some authorities who do seem to be minimizing sugar harms. I am not criticizing Chris’s position, but the conveyed interpretation these authorities have put on the research. Perhaps the usage “food toxin” or “dietary toxin” is better than “toxin”. Alcohol is a food which is also a toxin at increasing intakes.

    It is worth noting that the increase in degenerative diseases that follows adoption of western diet – cancers, tooth decay, heart disease, arthritis – do not seem to depend on hypercaloric intake or sedentary lifestyle. Nor does fatty liver (which can be produced by toxins, food toxins, or pathogens in normal weight individuals). Obesity may be the result of the addition of excess calories to the conditions that cause the other diseases. If we see it as part of this continuum, it perhaps helps to illuminate the role of food toxins.

    It is entirely possible that HCFS is more problematic than sugar, even if glucose and fructose levels are equalized. It is a grain product and is never entirely clear of immunogenic grain elements.

  50. george henderson says

    Look at this; http://stke.sciencemag.org/cgi/content/abstract/sigtrans;5/213/ec64
    G. A. Kyriazis, M. M. Soundarapandian, B. Tyrberg, Sweet taste receptor signaling in beta cells mediates fructose-induced potentiation of glucose-stimulated insulin secretion. Proc. Natl. Acad. Sci. U.S.A. 109, E524–E532 (2012).

    Researching the effect of fructose, without looking at the fructose-glucose combination is missing half the point; the sweetness of fructose increases the insulin response to glucose.
    Whether fructose is fattening might depend on one’s taste receptor phenotype.
    This nicely integrates the food reward and carbohydrate-insulin hypothesis aspects of fructose.

  51. Paleophil says

    The fructose-glucose combination is not always bad and has been shown in tests done on humans (albeit small and brief) to actually provide benefits. Wild fruits tend to contain both fructose and glucose and as I mentioned above, wild fruits tend to have more fructose and less sucrose than domesticated fruits (though there are even some wild fruits high in sucrose).

    Research suggests that fructose helps human subjects absorb fructose and modulate the glycemic effect of glucose without stimulating insulin secretion (in contrast to the findings of the Wei Wong mouse study–and as Chris pointed out, “The conversion of carbohydrate is less efficient in humans than it is in mice” and “The mice in the studies Lustig cites are eating huge amounts of fructose”):

    Moore, Cherrington, Mann, et al. Acute & fructose administration decreases the glycemic response to an oral glucose tolerance test in normal adults. J Clm Endocrinol Metab 2000;85(12):4515-19. http://jcem.endojournals.org/content/85/12/4515.full
    “low dose fructose improves the glycemic response to an oral glucose load in normal adults without significantly enhancing the insulin or triglyceride response. Fructose appears most effective in those normal individuals who have the poorest glucose tolerance.”

    Acute Fructose Administration Improves Oral Glucose Tolerance in Adults With Type 2 Diabetes
    Moore, Davis, et al. Diabetes Care November 2001 vol. 24 no. 11 1882-1887 http://care.diabetesjournals.org/content/24/11/1882.full
    “Low-dose fructose improves the glycemic response to an oral glucose load in adults with type 2 diabetes, and this effect is not a result of stimulation of insulin secretion.”

    Is Fructose Absorption in Humans Improved by the Addition of Glucose?
    Logan L. Davis-Wallace
    http://www.usc.edu/CSSF/History/2009/Projects/S1810.pdf
    “The addition of glucose could be used to improve the absorption of fructose in humans in high fructose containing foods and reduce symptoms of malabsorption (abdominal pain, gas, diarrhea, and bloating) from these foods.”

    Fructose Might Contribute to the Hypoglycemic Effect of Honey
    University of Science, Malaysia
    http://www.mdpi.com/1420-3049/17/2/1900/pdf
    “In view of the similarities of these effects of fructose with those of honey, the evidence may support the role of fructose in honey in mediating the hypoglycemic effect of honey.”

  52. george henderson says

    Let’s not forget that “safe starch” type roots and tubers (except oca) are sources of fructose and sucrose.
    This would surely approach the 10% or 7.5g “catalyctic” dose in meals that include significant carbs from beet, carrot, onion or sweet potato.
    See tables “food sources” below: http://en.wikipedia.org/wiki/Fructose

  53. Paleophil says

    If I’m reading the studies correctly, the 7.5g catalytic dose was just fructose and it was taken after consuming 75 g of glucose, and the only finding was that the addition of the fructose improved glycemic response to the glucose without other negative effects, not that 7.5 g fructose is necessarily the maximum safe consumption of fructose at a meal, so some people might be able to safely eat more. Did I miss something else?

  54. george henderson says

    Well, they’re saying you don’t need more than 7.5g (or 10% of glucose) to get this catalyctic effect.
    And it’s a dose that’s hard to avoid without restricting diet severely.
    But it doesn’t mean that more is harmful. Unless it’s HFCS, in which case all bets are off, because it’s not even a real food. And this is probably more important than we know at present; c.f. honey vs. sugar.

    If honey contains traces of antioxidants and “dirt” that assist its metabolism, are there corn-derived and other contaminants in HFCS that do the opposite? And does the more inert, less contaminated by processing, nature of cane sugar (but not so sure about beet) put it in the middle?

  55. Paleophil says

    In the studies it was 7.5 g fructose + 75 g glucose = 83.5 g total sugars, which is more than a lot of VLCers eat and wouldn’t consider as restricting severely, and it doesn’t even include starches. Plus, it may be that higher intakes of sugars are OK for some people.

  56. George D. says

    More total sugars, but I think only ketogenic dieters could avoid 7.5g fructose daily.
    What would fructose do to non-dietary sugar in the blood?
    Can it be causing mild hypoglycaemia in those sensitive to its effects, which drives higher-carb feeding and overeating?

    I don’t see a problem with sugars in people who are not sensitive to their effects; either glucose-intolerant through metabolic syndrome/DM2, or fructose-sensitive; (except of course as “empty calories”)
    I would define fructose-sensitive as, resolved to eat only one, but cannot stop after one; the “sweet tooth” if there are in fact any teeth left.

    This is less common with fresh fruit and strong-flavoured honeys, more common with dried fruit and refined honeys.
    When people do not have a sweet tooth, I’d consider it unlikely that fructose played a special role in any diabesity pathology.

    An interesting side-light on the “Empty Calorie” hypothesis:
    http://healthcorrelator.blogspot.co.nz/2012/07/lowest-mortality-bmi-what-is-role-of.html

  57. George D. says

    It would be very interesting to see how various metabolic diseases correlate with a history of “sweet tooth” (this would be better with behavioural observations, but self-reporting may be very accurate here).
    Would it be more present in those who developed normal-weight metabolic syndrome than those who became metabolically-healthy obese? That would be my prediction.

    • paleophil says

      George D. wrote: “This is less common with fresh fruit and strong-flavoured honeys, more common with dried fruit and refined honeys.”

      Right on George D.! In other words, not all carby or sugary foods are the same. There are “good carbs” as well as “bad carbs.” Surprisingly, raw fermented honey seems to be one of my better tolerated “carbs”–more so than “safe starches.” It has been fascinating to learn that there are many millions of years of history of consuming raw fermented honeys and nectars in our evolutionary tree.

      George D. wrote: “Would it be more present in those who developed normal-weight metabolic syndrome than those who became metabolically-healthy obese? That would be my prediction.”

      I’m thin, rather than obese, and I’ve never been diagnosed with any sort of metabolic syndrome because my fasting blood sugar measurements in physician’s offices were always excellent and my random blood draws were OK (though one reading was somewhat high due to having eaten some candy not long before the blood draw :-) which the nurse oddly said shouldn’t normally be a problem–don’t ask me why). Nonetheless, I seem to be far more sensitive to many easily-digested carby foods than most folks (producing zinc, potassium and maybe other deficiencies and symptoms thereof when certain carby foods are consumed beyond a limited level). I suspect that many people go undiagnosed on some health issues because fasting and random blood glucose tests are limited in effectiveness. Post-prandial BG (after eating most or every staple food) and mineral level tests seem to be better measures, but they require frequent home monitoring, which few people are willing to do, and which provides no income to physicians.

      I am HIGHLY sensitive to “sugars” (I believe that modern “sugars” contributed to my history of dental caries, periodontal disease, mineral deficiencies, acne, brain fog, etc.), yet I’ve found some “sugars” I seem to handle reasonably well and even derive health benefits from. I used to think that I would probably have to forever forego nearly all “carbs” and “sugars” until I found some that I seem to handle relatively well (though if they ever give me more problems than benefits, I’ll drop them). Keeping an open mind and being willing to experiment with many different foods paid off well for me (so far). YMMV

  58. Fara says

    Is there a safe sweetner to be used for baking? Stevia, raw honey, maple syrup, xylotil, erythritol? Anything?

    • Jasmine says

      Hi Fara :) 
      I’m a baker, cake decorator and sugar addict so I’ve been experimenting with sugar substitutes when I bake to determine what works best. 
      If you want something low in fructose then honey and agave are no good. They might be healthier than highly processed, refined white sugar but they are just as bad in terms of fructose. (PS raw honey isn’t raw anymore if you bake with it ;) )
      For baking things like cakes, cupcakes and cookies I replace half of the sugar in the recipe with a product called Natvia which is an Australian product made from stevia and erythritol and measures out in the same way as sugar. Eg one cup of sugar usually equals one cup of Natvia. It looks almost identical to white sugar and tastes very similiar but has a very slightly bitter aftertaste. 
       I have tried using Natvia to replace all of the sugar in recipes but the slight aftertaste was noticeable despite all the other components in the recipe, and to a baker and sugar addict such as myself it was unstisfying, so I stick to replacing only half of the sugar in a recipe. 

      I have also used Natvia in things like my own vegan ice cream and hot chocolate/coffee and it works very well, but with baking it does alter the final product because it doesn’t taste quite the same and also chemically it is not the same. 

      I’ve tried boiling Natvia to see if it would caramelise the same way sugar does, and it definitely does not :) I don’t recommend trying it lol :) 

      I’ve bought liquid stevia but haven’t cooked with it yet. But from what I’ve heard and read it’s a good alternative in terms of taste, no fructose, and calories. 

      Hope this helps :) 

  59. Fara says

    Hi jasmin,
    Thank you so much for your kind reply. I will check out Natvia. So many paleo recipes call for agave or raw honey. But as you mentioned there iare problems associated with those.
    I have used Stevia, and I agree. There is a fine line of where it tastes ok and then not so much. Bitter, chemical aftertaste.

  60. Missy Ruth says

    Um, no. Flat out, no. This is not a calorie issue – fructose in itself (yes, even in fruit) is processed in a potentially harmful way to the body, on a a cellular level, one cell at a time, regardless of how much is eaten or what else is eaten. Dr. Lustig’s research, advanced education in chemistry and awareness of how animal studies can be transferred (or not) to humans is profound – it is ridiculous to suggest that he would take research and lab studies that couldn’t be accurately applied to humans and state that “FRUCTOSE IS POISON” based on a flimsy, faulty premise. Are you serious here? I’m not certain what an L.Ac degree is, Accupuncture? Really? Please folks, go listen or RE-listen to Dr. Lustig (that’s Dr. Robert Lustig, Professor of Pediatrics in the Division of Endocrinology at the University of California, San Francisco) – basic one hour presentation before breathing a sigh of relief and turning again to fructose, even in moderation. Fiber makes it o.k. to consume fructose in very limited quantities, much like a bungee chord makes it o.k. to jump off a cliff, but it doesn’t make fructose any less toxic. Period. Fructose is a toxin, just like ethanol.

    http://articles.mercola.com/sites/articles/archive/2011/05/02/is-sugar-toxic.aspx

    • marzo says

      I suffered mild brain damage for a week from eating a small quantity of HFCS from jam. HFCS IS NOT NATURAL FRUCTOSE. GET IT THROUGH YOUR THICK SKULLS. HFCS is synthetic, toxic and I bet the human body doesn’t know what to do with it.

      I can eat kilos of ripe fruit without any problems. The science is wrong, do the tests on raw vegans. We have the cleanest bodies, inside and out.

    • Chris Kresser says

      Did you even read the article, and the cited studies? I was a speaker at the Ancestral Health Symposium along with Dr. Lustig and several others; in the Q&A of Dr. Stephan Guyenet’s talk, Dr. Lustig said that he has never suggested people avoid moderate fructose consumption from whole foods like fruit.

      I’d be curious to hear how you account for Dr. Sivenpiper’s findings, if fructose is so toxic? Most people here aren’t swayed by ad hominem attacks and appeals to authority. They’re swayed by evidence.

      • Paleophil says

        Chris Kresser wrote: “Most people here aren’t swayed by ad hominem attacks and appeals to authority. They’re swayed by evidence.”

        Here, here. I’m one of those people. And most people don’t buy jars of pure fructose at the supermarket, healthfood store or farmer’s market or pick gobs of fructose, conveniently heated and refined, off of fructose trees. As Marzo suggested, HFCS is not the same thing as raw fruits/berries (or raw honey).

        Missy Ruth: “go listen or RE-listen to Dr. Lustig”

        Instead of commanding us to watch the entire lengthy video again, why not provide some counter-evidence to the evidence that Chris, I and others provided on this very web page that you’re commenting on? Here are still more studies that support what Chris wrote:

        Hellerstein MK. De novo lipogenesis in humans: metabolic and regulatory aspects. Eur J Clin Nutr. 1999 Apr;53 Suppl 1:S53-65. http://www.ncbi.nlm.nih.gov/pubmed/10365981. “Only when CHO energy intake exceeds TEE [total energy expenditure] does DNL in liver or adipose tissue contribute significantly to the whole-body energy economy. It is concluded that DNL is not the pathway of first resort for added dietary CHO, in humans.”

        Acheson KJ, Schutz Y, Bessard T, Anantharaman K, Flatt JP, Jequier E. Glycogen storage capacity and de novo lipogenesis during massive carbohydrate overfeeding in man. Am J Clin Nutr. 1988 Aug;48(2):240-7. Free full text at http://ajcn.nutrition.org/content/48/2/240.long.
        “Glycogen storage capacity in man is approximately 15 g/kg body weight and can accommodate a [stored glycogen] gain of approximately 500 g before net lipid synthesis contributes to increasing body fat mass.”

        If fiber is the only thing that keeps small amounts of fructose-containing fruit from being poisonous toxins, then why do numerous studies show benefits from fiber-free honey consumption, as well as topical use, why did a study find real honey superior to “sham honey” (http://www.ncbi.nlm.nih.gov/pubmed/22063889), and why after adding small amounts of raw fermented honey to my diet did my fasting and postprandial blood sugar levels improve, my lifelong dandruff mostly clear up, my hair become softer and less oily, and a dental carie I have that a dentist and hygienist were urging me to get filled improve on its own (the hygienist was surprised, to say the least) despite the added sugar? And why do my blood sugar, dandruff and hair all worsen again if I go too long without the RFH? I limit my intake, yes, but the notion that only fiber keeps fructose-containing foods from being pure poisons is an unproven assumption.

        Marzo wrote: “I can eat kilos of ripe fruit without any problems.”

        While I don’t think that raw vegan diets are optimally healthy and have seen countless reports from raw vegans of dental problems, B-12 deficiencies, coldness, and so on, I have noticed that Internet images of raw vegans–particularly those that eat lots of fruit–appear the thinnest, generally, of all dieters. If fructose and fruit are especially fattening, why should this be? Emaciation seems to be a bigger risk with fruit intake than obesity. Doubters can check the images at various dietary forums themselves. There’s no apparent obesity epidemic among raw vegans.

        • marzo says

          ” and why after adding small amounts of raw fermented honey to my diet did my fasting and postprandial blood sugar levels improve, my lifelong dandruff mostly clear up, my hair become softer and less oily, and a dental carie I have that a dentist and hygienist were urging me to get filled improve on its own (the hygienist was surprised, to say the least) despite the added sugar? And why do my blood sugar, dandruff and hair all worsen again if I go too long without the RFH? I limit my intake, yes, but the notion that only fiber keeps fructose-containing foods from being pure poisons is an unproven assumption.”

          Honey contains a lot of antimicrobial peptides which kills of fungus on the scalp and microorganisms in the GI tract. Also, you most likely went the paleo route and ate liver to repair your caries. Liver contains vitamin A,D,K.

          Our immune system produces its own antimicrobial peptides to kill off excess microorganisms. Vitamin D, singing and exercise have been found to increase and stimulate their release. Vitamin A has been found to keep their levels high. So.. inactivity and a vitamin D deficiency is the ultimate cause of all those problems. Plus halitosis, bad breath.

          “While I don’t think that raw vegan diets are optimally healthy and have seen countless reports from raw vegans of dental problems, B-12 deficiencies, coldness, and so on, I have noticed that Internet images of raw vegans–particularly those that eat lots of fruit–appear the thinnest, generally, of all dieters. If fructose and fruit are especially fattening, why should this be? Emaciation seems to be a bigger risk with fruit intake than obesity. Doubters can check the images at various dietary forums themselves. There’s no apparent obesity epidemic among raw vegans.”

          Proper raw vegan diets by healthy long term raw vegans are extremely healthy. Karen knowler, Tonya kay and Nathane jackson come to mind.

          Those skinny vegans aren’t exactly what I call real raw vegans. I call them the fruitarian/811rs fat phobics. Raw vegans eat lots of nuts(to insulate cell membranes and for neurogenesis), fruits and leafy greens.

          Dental problems along with halitosis(bad breath) are the cause of an overgrowth of harmful bacteria in the mouth which is directly the cause of low antimicrobial peptides in saliva. Like I stated above, vitamin D deficiency and inactivity will cause low levels of antimicrobial peptides.

          Vitamin B12 deficiencies happen because people don’t know how humans co-produce vitamin B12 with bacteria. I do infact and not planning to release the information any time soon. We are definitely not meat eaters unless we need it to survive and we don’t need meat for brain evolution.

        • Onur says

          One’s mental state and his/her mindframe may be even more important than the diet they make. Everyone chooses and adheres to a diet depending on them. Also the motivation to add a photo can be influenced by many factors, so I do not think the fruitarians, 811′ers, and whatever diet followers seem physically healthier is a clear indication to how good the diet is.

  61. says

    http://www.sciencedaily.com/releases/2012/09/120913104121.htm

    (evidence of how fructose is harmful, though not that it is fattening)
    It probably doesn’t take much DNL to make a fatty liver. And the DNL rate on a very low-fat diet must be high just to sustain life. There are a lot of variables, between diets, races, body types, and I don’t think any one study can capture the range of possible responses, or serve it up as a mean value without distortion.

    As kids we ate tons of sugar and obesity was then very rare. Linoleic acid (not prominent back then) may be the toxin that primes adipocytes to expand. We’re also talking about specific genetic combinations and epigenetic triggers – not everyone who eats the same food gets fat, not everyone who smokes 60 a day gets lung cancer.

    As for the raw vegans, their diet is basically antinutrient and I would not expect them to fatten. Fruit is not a great source of calories unless you dry it or extract the juice.
    But if you’ve become sensitive to carbohydrate for some reason, then fruit needs to be counted as carbs.

    • marzo says

      The link of the article you posted is very bias.

      All those problems are the cause of obesity. People eat too much because they are deficient in a lot of vitamins and minerals, especially magnesium. Plus obese people have hyperlipidemia(high blood fat) which will always skew the research.

      The omega 6 ratio theory doesn’t apply when eating whole foods such as nuts. The linoleic acid research only applies when a person eats high omega 6 “oils” since they lack vitamins and minerals.

      Omega 6 reactions in the body:

      delta 6 desaturate(enzyme) + Linoleic acid + Vitamin C, B3, B6, magnesium, zinc = DGLA -> leads to the production of anti-inflammatory eicosanoids and inhibits the production of AA.

      “In humans, the activity of D6D(delta 6 desaturate) declines with age and in various diseases including arthritis, diabetes, hypertension, eczema, and psoriasis. In addition to this, lifestyle factors such as stress; smoking; excessive consumption of alcohol, of linoleic acid, and of saturated and transfatty acids; as well as nutritional deficiencies of vitamin B6, zinc, and magnesium inhibit D6D.”
      Source: http://www.shikai.com/publications/GLA-A%20Natural%20AntiInflammatoryAgent.pdf

      delta 5 desaturate + Linoleic acid – Vitamins and minerals = AA -> leads to the production of inflammatory eicosanoids.

      Nuts contain vitamins and minerals. Oils don’t.

      Fruit, especially ripe and organic, without organophosphates(pesticides), is extremely healthy and a great source of calories, organic water, vitamins and minerals. Fruit is a poor source of fat to insulate cell membranes but thats where nuts come in. Also, don’t confuse raw vegans with fruitarians/811rs. Raw vegans aren’t fat phobic.

      Remember that nature has always had it right. Corporations gotta stop manipulating foods and selling us toxic products. Above all, people gotta stop making excuses for the crappy food they put in their mouth.

    • paleophil says

      High Fat Hep C Diet wrote: “(evidence of how fructose is harmful, though not that it is fattening) … As for the raw vegans, their diet is basically antinutrient and I would not expect them to fatten. Fruit is not a great source of calories unless you dry it or extract the juice.”

      So you agree with Chris’ point in this blog post that fructose and whole fruits are not uniquely fattening for most people, yes? BTW, fruits are not especially high in antinutrients, but emaciation is nonetheless more of a problem among fruitarians and 811ers than obesity. Some traditional cultures have special fattening diets and I’ve yet to come across one that includes fruit as a staple.

      • marzo says

        By most people, you mean those that are not obese, then yea I agree. Like Chris states in the blog, its about excessive intake. In my opinion, Chris should of just wrote that obese people suffer from a mental disorder and over eat, that’s the truth.

        Fruit is not antinutrient unless its unripe(high in phytic acid) and hybrid, which most fruits are in the supermarkets.Tropical fruits from the tropics contain twice the amount of protein, vitamins and minerals. Fruit can be fattening if someone is able to eat 7+ kilos of fruit per day to get enough sugars for fatty acid synthesis and enough vitamin D to handle those amounts of sugars but fruit is way too low in omega 6’s which will lead to mental retardation if only eating fruit.

        We agree that there isn’t anything wrong with fruit. Its just sad that all these low carbers blame foods for their excessive eating habits.

  62. says

    I always defer to the likes of Richard Mackarness, Bary Groves, and John Yudkin, who were into high-fat diets for weight loss before Dr Atkins. They all included some fruit. Same with most of the old diets in Gary Taubes’s books.
    Fruit consuming cultures of Afghanistan, Pakistan and India did see obesity and diabetes among the rich who ate the most fruit. Grapes and dates and melons might be prime culprits, but I think whole citrus might be benign, as citrus flavonoids like naringen activate PPAR-alpha, the same gene that low-carb dieting and calorie restriction activate. I presume this is where the grapefruit diet comes in.

    • marzo says

      The truth is that insulin inhibits lipolysis. Fruit inhibits the body from using the fats from the meat as fuel. In reality, the fault is not of the fruit but simply the result of our domestication. If we lived out in nature, we wouldn’t have meat and fruits in abundance easily available to us around the corner.

      • Paleophil says

        Interesting, marzo, do you have any references on that I could read? That might help explain why heavy eaters of fruit tend toward emaciation rather than obesity (as many LCers claim for some unknown reason).

  63. says

    Antinutrient diet in the sense that the diet in general is not rich in nutrients (energy or micronutrient) and is high in antinutrients; most fruits are poor sources of energy for volume consumed; those that are not, such as dates or sultanas, probably are potentially fattening. Fruits may also be antinutrient if excessive consumption causes rapid elimination.

  64. marzo says

    Think realistically and forget your domesticated ways. Where would you get 2 liters of water per day without the tap?

    You are forgetting that fruit digests a lot quicker than a piece of meat. Its easy to eat and digest a lot of fruit in a short amount of time.

    • says

      I’d get it from the river, or the spring at the back of my house. There’s even this thing called rain sometimes.
      fruit digests quicker than meat? I’ll bet 1,000 calories of fruit doesn’t digest as quickly (or quietly) as 1,000 calories of meat.
      A lot of fruit is not a lot of nutrition, unless it’s coconut or avocado etc.

      • marzo says

        Living in low-carb land.

        Its not possible to ingest the required amount of water per day from outside sources without contracting a bacterial infection. There is a reason why water is disinfected.

        Carbs digest instantly while fats require bile. 1,000 calories of meat requires a good 8 hours while 7,000+ calories of fruit digest in the same amount of time. The only reason why fruit ferments is because you eat it after eating meat. It basically sits there on top of the meat to rot.

        “A lot of fruit is not a lot of nutrition, unless it’s coconut or avocado etc.”

        False again. Fruit may be low in protein and fats but its high in vitamins and minerals. Where would you get 4.7g of potassium without fruit or leafy greens?

        Take into account that no primate on this planet eats only one type of food. Fruit is meant to be part of a healthy balanced diet.

        • says

          I wonder how or why 2 litres of water made their way into this discussion. Marzo, you say

          “Its not possible to ingest the required amount of water per day from outside sources without contracting a bacterial infection.”

          But elsewhere you say

          “Our immune system produces its own antimicrobial peptides to kill off excess microorganisms. Vitamin D, singing and exercise have been found to increase and stimulate their release. Vitamin A has been found to keep their levels high. So.. inactivity and a vitamin D deficiency is the ultimate cause of all those problems.”

          If you are in a survival situation your concern is with energy and protein – this is what I mean by nutrition. (See how far potassium and vitamin C get you when you are starving). Whatever whole food you eat, whether meat of vege, will supply micronutrients, but micronutrients were not what australopithecus was looking for. Meat is a rather good source of potassium BTW, along with ash from cooking fires which was used as seasoning.
          I’m not opposed to eating fruit. But humans can and do get by without it, of necessity, without suffering any consequences as long as they have fresh, whole food of other origin.
          There is as much ascorbate and potassium in potatoes as in fruit, with more energy, and there is enough in fresh meat to support health.
          Man, by the way, is the only animal that needs to drink enough water to urinate and sweat copiously. Our requirement for water is quite unusual and hard to explain in evolutionary terms.

            • Paleophil says

              “7,000+ calories from fruit?

              Was that for the Guinness Book of World Records?”

              Nope, Durianrider reports that he has eaten more (Friday Q&A: is 70 Bananas a Day too Much? #448, http://www.youtube.com/watch?v=56qwAxpAMD), which I don’t recommend (Paul Nison talks about the downside of excessive fruit intake in that video and points out that TC Fry and other heavy fruit eaters had suboptimal health). While he fibs on a lot of things, I believe him on that, given his obsession with fruit.

              • marzo says

                TC Fry ate a poor diet all his life, was inactive and Vitamin D deficient because of his inactivity. Paul Nison is the same way. His eye bags tell us that he has adrenal fatigue from the lack of Vitamin D.

                What I do believe is that eating only fruit is bad. No mammal on the planet eats one type of fruit, plant or animal. What I do know from experience is that there is a big difference between eating only fruit(alkaline) and leafy greens(neutral), and eating fruit, leafy greens and nuts(acidic, growth) in no particular ratio. Its about the acid/alkaline balance.

                DR is a twig that eats too many bananas. Bananas are too high in pesticides, norepinephrine, too low in Vitamin A and Omega 6′s. Norepinephrine in an inactive individual and the lack of Vitamin A/Omega 6′s promotes muscle loss. I avoid bananas and eat a lot of leafy greens for the Vitamin A, minerals and best protein source.

                I’ve easily eaten more than 7000+ calories of ripe cantaloupe in one summer day. Then fasted as only natural in nature.

                Everything is bad for the human body when someone is domesticated.

            • marzo says

              Once a person is active regularly and is accustomed to intermittent fasting. Its all about eating unlimited quantities when hungry and fasting naturally.

              Ripe fruit is all water with very little fiber.

          • marzo says

            Contaminated water can contain intestinal parasites.

            We aren’t in a survival situation and we have technology(tool) to feed outselves the best food. Meat is a great source of compacted nutrients. So.. What drives brain evolution? What specific molecule? I already know but lets hear it.

            I don’t mind if people eat meat. Just liberate the animals before the whole planet turns into a desert. When the animals are liberated, no pesticides are needed, the chickens eat the insects and the cow dung enriches the soil.

            “There is as much ascorbate and potassium in potatoes as in fruit, with more energy, and there is enough in fresh meat to support health.”

            Its so easy to get solanine poisoning from eating potatoes. Solanine is a neurotoxin.

            “Man, by the way, is the only animal that needs to drink enough water to urinate and sweat copiously.”

            Enough water to keep the brain hydrated and the excessive sweating only happens in those that eat animal flesh. I don’t need deodorant.

  65. paleophil says

    Antinutrients are “compounds that inhibit the normal uptake or utilization of nutrients” (http://www.expertglossary.com/science/definition/antinutrient) rather than foods low in nutrients, and antinutrients are highest in grains and other seeds, nuts and vegetables. I know of no prominent LC proponent who claims that fruits or honey are high enough in phytic acid or other antinutrients to be a significant problem, so rather than go off further on that tangent, I’ll try to bring the discussion back to the crux issue of this blog post (analysis of the hypothesis that fructose is a uniquely fattening poison and that fructose or sugars are the key dietary cause of obesity without additional cofactors like flavorings and other brain-reward stimulating elements) with some questions. Wouldn’t the foods that *cause* obesity to begin with be likely a worse problem than the foods that only contribute to obesity after it has set in, and isn’t it possible that once the foods that cause obesity are removed, that the foods that only contribute after obesity has set in might eventually become less of a problem? Shouldn’t we be focusing first on the foods that actually cause obesity and ill health?

    If we focus on “carbs” or “sugars” or “fructose” as the issue, then that leads to people eating stuff that tends to get advertised and promoted at LC sites like those of Jimmy Moore (I give him some credit for becoming less positive about Splenda and more so about food quality), Johnny Bowden, and others–such as LC cereal, Carbquik Baking Mix, Atkins low-carb “snack” and “dessert” bars, Atkins LC penne pasta, etc. None of these foods are found in traditional societies. They cannot explain the relative absence of obesity in those societies, nor among the excessively skinny datorade-drinking, juice-feasting, fruit-gorging fruitarians and 811ers (some of whom were previously overweight or obese), nor the fat-loss success of Seth Robert’s sugar-water appetite-reduction technique, nor have these new LC foods been tested for long. They effectively make guinea pigs of the dieters that rely on them.

    The carbs/sugars focus also leads to fear of traditional foods like raw honey, whole fruits, and roots and tubers and to people criticizing those who dare to eat them or speak positively about them. Yet none of these traditional foods has been connected to obesity. There seems to be more at play here than the reductionist hypotheses regarding “carbs,” “sugars,” or “fructose” by themselves.

    Even if fructose were uniquely fattening, if you limit yourself to traditional foods and don’t gorge on honey, fruit juice or dried fruit every day, it’s difficult to consume a lot of fructose or other sugars, and they aren’t in the heated, refined, filtered and concentrated forms used in the studies that filter out or destroy most of the nutrients and cofactors found in wild and heritage fruits and honeys. As Dr. Lindeberg pointed out, a daily fructose intake equivalent “to 4-5 kg of pineapples” is widely considered safe. Not many people aside from fruitarians and 811ers eat that much fruit. So traditional foods are a win-win—they avoid both modern foods and the massive intakes of processed fructose in the mouse studies.

    If someone has evidence that fructose is uniquely fattening in an isocaloric state, or that links whole fruits or raw honey to obesity, please share it. You’re not likely to convince Chris or many others with opinions and assumptions.

    • Martin rown says

      I am in agreement. I have become very interested in Ray Peat and his work. I have been eating in that fashion for a while now and am thriving. I eat a lot of fruit and freshly squeeze orange juice etc.

      I genuinely believe the paleo template and ray peat can live in harmony.

    • says

      I think that fibre in large amounts is a well-established antinutrient.
      In order to get lots of energy from fruit you would have to consume enough fibre to speed it through.
      This is why our ancestors a few hundred years ago didn’t trust fruit and often suffered from scurvy when it was available.

      • marzo says

        Hahaha!!! Where did you read this nonsense? What about ripe oranges?

        Can we stop with the bias?

        Fibre of vegetables and “unripe” fruits (is a well-established antinutrient.)

        Those on ships had scurvy and the europeans living in artic regions had scurvy.

        The problem isn’t natural fructose. The problem is organophosphates(pesticides) that corporations spray on fruits and organophosphates that plants absorb then tranfer inside the fruit which leads to Demyelinating disease.

        http://en.wikipedia.org/wiki/Demyelinating_disease

      • paleophil says

        George Henderson wrote: “I think that fibre in large amounts is a well-established antinutrient.”

        Kudos–overstated, but now I suspect that you’re starting to get somewhere. I researched that in the past while trying to figure out why fruits were more of a problem for me than 99% of people. While fiber is not regarded as a true antinutrient, some believe that it can have antinutrient-like effects in large amounts (Suite101: Antinutritional Factors: Phytate and Oxalate in Vegetarian Diets | Suite101.com, http://suite101.com/article/antinutritional-factors-phytate-and-oxalate-in-vegetarian-diets-a304396#ixzz27fO75W8b), though the data is mixed and may depend on the contribution of additional factors (such as true antinutrients, gut dysbiosis, insulin resistance, and perhaps other unknown factors) in combination with the effect of fiber. In one study, the juices of fruits and vegetables were found to increase all measured levels of minerals, whereas the fiber in whole fruits and vegetables caused small reductions in zinc and copper (Effect of fiber from fruits and vegetables on metabolic responses of human subjects, II. Calcium, magnesium, iron, and silicon balances, http://ajcn.nutrition.org/content/32/11/2307.full.pdf). So, despite “common knowledge” about sugars being the ultimate poisons, it was fiber that was linked to mineral deficiencies, rather than “sugars.”

        My understanding is that grains, legumes and whole vegetables contain far more fiber than fruits and honey. If fiber is the key issue, then fruits and honey are not the main bogeymen.

        • marzo says

          Over thinking it and trying to find studies to fit your view point isn’t going to convince anyone.

          The article you pointed out is full of bias. Healthy humans have oxalate degrading bacteria in the colon to degrade oxalate from RAW leafy greens.

          The majority of fruits in stores are picked before they have gotten a chance to ripen. Orange is a fruit that ripens on the tree. Unripe fruit: High in fiber, oxalates, phytates, etc.. Why? The fruit needs to defend itself from incompetent humans.

          Insulin resistance is caused by excess salt intake and has nothing to do with diabetes even though its found in diabetics. Correlation isn’t causation.

          ” So, despite “common knowledge” about sugars being the ultimate poisons, it was fiber that was linked to mineral deficiencies, rather than “sugars.” ”

          Phytates have an affinity for heavy metals. Not minerals.

          Mineral deficiencies are the result of not eating them in the first place and the epidemic of Vitamin D deficiency. Vitamin D is needed for the absorption of all minerals.

          Grains, legumes and vegetables contain far more damaging molecules than fiber.

          • paleophil says

            More thinking and presenting of evidence and less biased assumptions would be more convincing on your part. You didn’t even bother to present evidence, so there’s no need to refute anything.

  66. Jasmine says

    I think the most dangerous aspect of fructose is its ability to create a hostile online evironment on nutritional discussion boards :)

  67. Jasmine says

    I think the most dangerous aspect of fructose is its ability to create a hostile online environment within nutritional discussion boards :)

  68. Sarah says

    Hi Chris,

    this was really interesting, thanks. I would love to know though – what are your views on the consumption of fruit in very large quantities (like in the case of those following the 80 10 10 diet which relies on the consumption of a very large amount of fruit – 80 percent of daily caloric intake)?

    thanks,
    Sarah

  69. says

    http://ajcn.nutrition.org/content/96/4/727.abstract

    Effect of short-term carbohydrate overfeeding and long-term weight loss on liver fat in overweight humans

    Conclusions: Carbohydrate overfeeding for 3 wk induced a >10-fold greater relative change in liver fat (27%) than in body weight (2%). The increase in liver fat was proportional to that in DNL. Weight loss restores liver fat to normal. These data indicate that the human fatty liver avidly accumulates fat during carbohydrate overfeeding and support a role for DNL in the pathogenesis of NAFLD.

  70. David says

    Sugar is not the problem. I have been sick and have had many health issues. Since i follow RAY PEAT and eat up to 600g of sugar ( mostly fruit ). I have gained muscle mass 15kg and lost my body fat. How can sugar be a bad guy? I have tried every single diet out there and nothing helped. He is genious and im eternely grateful to him!

  71. mary says

    Hi, I have been trying to research agave syrup and whether or not it is an ok alternative to refined sugar. And where it stands next to honey. I am confused by this post because of the previous post (2010) about the 3 causes of obesity, which said that fructose was one of the causes and should be avoided. Can someone please clarify?

  72. says

    I have a quick question- Are blended fruit/vegetable smoothies okay? I usually eat a fruit+veggie smoothie with whey protein powder for breakfast.

  73. says

    Chris. I avoid fruit mainly because it interferes with my ketosis more heavily than other carbohydrates.

    I compete in boxing and find my energy level to be better when I’m keto-adapted. Am I missing out on anything by taking fruit out of my diet?

  74. Chris Evert says

    I agree that Fructose is evil for liver more than alcohol . I am a 25 yr old non-alcoholic ( not even a drop of alcohol till now) , but recently i was diagnosed with grade-2 fatty liver. My liver is enlarged by nearly 20% . At the same time i am over weight , no exercise and is a sweet-holic .

    I stayed off alcohol to munch on sweets thinking they are safer but i was wrong . Now i have been asked to cut down on all sweets and fried items.

    Hopefully i will be able to shed my weight and save myself

  75. Julie says

    I’m a bit late to the conversation, but I’ve gathered from reading the article and browsing the comments that I don’t need to be worried about the fructose in my 4 year old daughter’s multivitamin. We don’t have soft drinks in the house, rarely have sweets and when we do, there is a limit on how much.

    Am I on track? Thx

  76. marcus volke says

    The problem with fructose isn’t that it gets converted to fat…the problem is that it is metabolized by the liver (like alcohol) and this process creates toxic metabolites and can harm the liver, potentially contributing to fatty liver disease.
    Every human trial I have read comparing glucose to fructose in isocaloric settings has concluded that fructose is more harmful – it is more likely to promote weight gain and contribute to metabolic syndrome. I did not see any of these human trials covered in this article, there’s really nothing convincing written here. The only thing I agree with is that studies show that fruit consumption does not have the same harmful effects as added fructose.

  77. says

    Fructose is not metabolized in any way like alcohol. It is a gross exaggeration to say ” it is more likely to promote weight gain and contribute to metabolic syndrome.” If you maintain a high total carbohydrate intake, fructose may be worse than glucose but effects are small. We covered human trials in our review which provides a balanced perspective: http://www.nutritionandmetabolism.com/content/pdf/1743-7075-10-45.pdf

    Support your local biochemist.

  78. Jamal Jafri says

    I read somewhere that fructose is ten times more reactive in producing glycation products with haemoglobin than an equivalent blood concentration of glucose. Is this true?

  79. says

    Jamal, fructose is more reactive than glucose but there is almost never an equivalent mount of fructose in the blood. Fructose is cleared rapidly while glucose is maintained at constant levels. Most glycated hemoglobin comes from glucose. This whole discussion follows from the opinion of Rob Lustig who is not a biochemist and whose obsession does not follow from any great new experiment. He just got a bug in his ear some time and with his superficial understanding of biochemistry became a zealot.

    We all see that kids have too much availability to sugar and we see just the way Lustig sees it. We all know it is hard to regulate kids intake of sugar but it is also hard to regulate their intake of starch and it is hard to do get your kid to go to bed on time. But fructose is not a poison. It is not addictive in the way that cocaine or alcohol are. We know that bananas don’t hurt us unless we put them on peanut butter and banana sandwiches and eat too many. For many things, starch may be worse than sugar — diabetes for example. The science says that reducing carbohydrate is therapeutic if you are overweight or have diabetes. If you think that it is because of the fructose, cut that out first but if you take out fructose and put in glucose, you are just gambling and you don’t even know if the odds are in your favor.

    Support you local biochemist.

  80. Julie says

    Thanks NSku for your comments. I find it easy to see the 2 categories: fructose with naturally occurring fiber vs. fructose without fiber (as a food additive).

    I would also caution anyone taking supplements including children’s multivitamins who is also concerned about fructose to read the inactive ingredient labels. I was surprised to find fructose in my child’s Child Life multivitamin which is what prompted my search that led me here. This is a helpful discussion. Thank you all and blessings

  81. Aaron Barnden says

    I recently discovered Dr Ray Peat, and, like many of his writings and interviews, this article in particular has thrown my world view into disarray: http://raypeat.com/articles/articles/sugar-issues.shtml
    I would most appreciate anyone’s insights into the research Peat has cited in this article (preferably, down to the minutiae). Chris’s article on fructose has made me more receptive to Dr Peat’s ideas, but I still feel like I’m floating in limbo between ‘Fructose is poison’ and ‘Fructose is the ambrosia of the Gods’

    • says

      Aaron,
      I thought that we offered a balance appraisal of fructose http://www.nutritionandmetabolism.com/content/pdf/1743-7075-10-45.pdf
      But an important point is that we don’t know that much about metabolism, any metabolism. We know a lot compared to 100 years ago but there are major missing pieces. I usually describe metabolism as like American football where many things are going on and you can follow the quarterback but that may not be the key to the play. I have not read all of the 8,000 Ray Peat wrote but he and others have presented key plays, highlights if you like, but in many case, we still don’t know who won the game.

      On your question, though, fructose is not a poison and I have had chocolate mousse that has transcendent quality but why expect such extremes?

      Support your local biochemist.

  82. Gail says

    My daughter and I have both noticed a difference in soft drinks (which I don’t drink anymore, thank you). I sip a sugar sweetened drink, put it down, and I’m done. With high fructose corn syrup, I gulp it down and reach for another. I don’t know if there are other differences, but these is a difference.

  83. says

    It’s been a while since I watched “Sugar: The Bitter Truth” but I don’t remember thinking “I shouldn’t eat fruit” after watching it. I remember thinking this is a really good message for soft drink consumers to hear.

  84. John McDonell says

    There are two main ways (I’ve found) to eliminate/reduce the gout/sciatic nerve pain. There are 5 cell types that have no natural ability to shut off intake of excessive amounts of glucose… and most other sugars. One of these cell-types are neurons.
    TRICK ONE ::: vitamin C shares the same transport mechanism as glucose to cross the blood-brain barrier To restrict excess glucose from entering nerve tissue AND REDUCE PAIN, eat some vitamin C (to limit spiking)
    TRICK TWO ::: The brain operates quite well on the fuel ketones. SO GLUCOSE AND KETONES ARE BOTH ‘NATURAL’ ENERGY SOURCES. The strategy to eliminate cancer (& used by diabetics) is to stress the natural saturated fats to create a state of ketogenesis. In this state ketones (instead of glucose) is employed as the sole energy source for cells. Cancer cells, cannot survive without glucose as their fuel.
    To severely restrict carbohydrate (sugar) intake in the a.m. until 3p.m. >>> exercise strenuously >>> pig-out with loads of carbs to purposely cause a spike of cortisol/insulin to cleanse arterial plaque, (etc). The effects of this ‘spike’ is soon over. And will not disturb sleep, if eaten 2 hrs before bed. The technique is called Carb Backloading was introduced by John Keiffer for bodybuilders. This technique should also be very useful to mitigate nerve pain from a sugar overload.

  85. Wellshii says

    Agree Chris, fruit has many nutrients vs the so called bad fructose. Rather have a fruit than an alcoholic beverage ,that’s for sure.

  86. Peter Hutchison says

    Hi Chris, I’d be interested to hear your thoughts on this http://www.abc.net.au/radionational/programs/healthreport/the-obesity-epidemic/3240406 from Dr Robert Lustig
    (Professor of Pediatric Endocrinology University of California) – essentially some compelling research that unintentionally uncovered some interesting effects fructose has on signals telling the brain when enough food has been eaten and also another interesting side effect of incorrect signals for low energy levels that result in abnormal lethargy and significant discomfort when exercising.

  87. Nads says

    Fruit makes me hungry full stop (period). I used to think it was my imagination. If I have it now it has to be in combination with fat and protein. My food addiction was actually a fructose addiction. I think it does affect peoples’ brains differently.

  88. Tale says

    This all seems very reasonable, and I always applaud Chris’s scientific look at the research, but I am a little surprised to see no mention of this in an ancestral health context.

    I used to eat a lot of fruit (and grains and sugar). I’ve dialed way back on the fruit, mainly now some berries in a typical week and whatever little scraps of various fruits there are left over after one of their meals (which means on the order of barely a bite of a peach or pear or apple). I’m open to the idea that I could be eating more, but do wonder what the essential value of it is to me, especially in the context of evolutionary biology.

    The way I see it, there were very, very few cultures that got to eat fruit on a daily basis the way it is recommended by mainstream nutritionists in the modern era. My ancestry in particular is northern European. Seasonal fruit was more the norm, and with that there’s also a reasonable argument to be made that its main utility there was to put on a little extra insulation for the bleak months of winter.

    So great maybe fructose isn’t so bad for me as some quarters suggest (or maybe it is; I had fatty liver and metabolic syndrome before going Paleo). Maybe it shouldn’t be on the “avoid as much as possible” list. How much then? “Everything in moderation,” is of course not a terribly useful measure.

  89. Kimbo says

    You can’t have “an isocaloric diet”. Isocaloric means “having the same number of calories”. The word only makes sense if you are comparing two or more diets. The concept is relevant to the debate about whether a low carbohydrate diet causes weight loss only because it makes you eat less calories, or even when compared to an isocaloric higher carbohydrate diet.

  90. says

    Ideally, we would combine fruit with greens for balance and to avoid blood sugar spikes. Today I blended orange and pineapple pieces with water and had a cup of that with about
    1 1/2 tsp. barley grass powder. Of course, we can also blend fresh greens with fruit.

  91. says

    Excellent article Chris. So good to read well thought out and researched content.

    Just finished reading the Honey Diet, which suggests that the liver deals with fructose from honey better/faster than other sources, because of the other nutrients in it. I’m wondering if anyone has figured out what these nutrients are so we can combine them from high-fructose corn syrup to facilitate glycogenesis.

    Another reason for desiring this is because fructose is known to produce 10x the amount of glycation end products compared to glucose. Fructose can help us keep our vitality topped up, but we need to minimize glycation end products to insure flexible arteries and veins in our older ages.

  92. says

    There are minor impurities in honey which alter the taste but I would be very surprised if the liver deals with fructose from honey any different than any other source.

    Also, fructose, from any source is glycogenic. Under many conditions, more than glucose. Historically fructose was known as a glycogenic substrate.

    Finally, fructose reacts much faster than glucose but fructose is cleared while glucose is maintained at constant levels. Most glycation end products come from glucose not fructose.

    Possibly of value, our perspective on fructose:
    http://www.nutritionandmetabolism.com/content/pdf/1743-7075-10-45.pdf

  93. petter says

    Find this post highly enlightening.
    Or, at least, it’s a very plausible hypothesis Chris presents:

    Namely; if you overeat, most easily done with lots of fats and refined carbs,
    the fructose can be very problematic. If not, you might be relatively fine.

    Just look at these guys who gluttonize in massive volumes of mangos and bananas etc,
    but still experience good health, at least for some years (hey I wouldnt recommend it)

    This vid show some examples on how much fruit you need to eat get as much fruit you
    have to eat in order to comsume as much fructose as that guy in “super-size me” did:

  94. Colin B Maharaj says

    Hi folks,
    This article misses a few points, but before that, in Lustig Presentation he DID mention DNL with medical students. This was at 64m:30s. I remembered this well because he said something funny….”Normal medical students, if you can call them normal – taking in a glucose load ….then a fructose load….”

    Another thing that is misrepresented here, sorry for saying, is that while fruit may appear to have been targeted, I see no evidence in the lecture. Dr Lustig did mention that fruit has fiber and that fiber mitigates how rapidly the sugar is absorbed. And the REAL problem is fructose without the fiber, or fiber-less food and that most processed foods manufactures take out the fiber to stop it from spoiling and on top of that add in the fructose to make it taste good.

    To me the entire first 20 mins was devoted to the problem of over consumption. Most of his other interviews are testimony to this. In one interview he says how much not to cross for men and for women.

    So over consumption is the problem and was identified in the lecture, because it is unknowingly in everything.

    Finally what I find most interesting and is the most important factor that made me avoid sugar (and most processed foods) is that there is no reaction in the body that requires (fructose) sugar, as a precursor for some physiological function.

    I think people should watch the video a few times, it took me a while to figure it out, since I am not a biochemistry student.

  95. says

    “there is no reaction in the body that requires (fructose) sugar, as a precursor for some physiological function” is a bon mot that sounds great but, in fact….

    The fructokinase reaction converts fructose to F-1-P. Physiologically, F-1-P is a positive allosteric effector of glycogen synthase and glucokinase and a negative effector of glycogen phosphorylase (breakdown of glycogen), that is, fructose calls for glucose uptake and enhances glycogen storage. F-1-P is converted to glycolytic intermediates just like glucose.

    These physiologic functions evolved because fructose is part of human biochemistry.

    http://www.nutritionandmetabolism.com/content/pdf/1743-7075-10-45.pdf

    Support your local biochemist.

  96. jake3_14 says

    The fundamental issue for me with Chris’ article is the assertion that fructose is harmful *only* in the context of eating too many calories. Taubes thoroughly debunked the myth of the CICO paradigm of weight in his two books. So, why does Chris implicitly endorse this idea?

  97. Susan says

    I am not an expert except in what happens to my body in reaction to what I put in it was but I have read extensively and try to understand both sides of the coin.
    I am really concerned that that you
    1) seem to be saying that most of us who are overweight are not eating excess calories?! And therefore we can eat fructose with no detrimental effect. What planet are you living on?
    2) you opine that fruit is satiating so people tend to eat less in terms of other calories. I find fruit most unsatisfying and cannot be the only person …
    So yre you saying we can all eat as much fructose and high fructose corn syrup as we like no problem?

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