A streamlined stack of supplements designed to meet your most critical needs - Adapt Naturals is now live. Learn more

Is Refined Sugar Really Toxic?


Last updated on

refined sugar, refined white sugar
Is refined white sugar really as toxic as we've been led to believe? istock.com/YelenaYemchuk

So far in this series, I’ve covered a variety of ‘alternative’ sweeteners: natural sweeteners like honey and stevia; artificial sweeteners like aspartame; and sugar alcohols like xylitol.

But what about plain old white sugar? And what about the increasingly common industrial sweetener, high fructose corn syrup? These two get a pretty bad rap, even from mainstream media, and although much of their reputation is deserved, there are some misconceptions that I’d like to straighten out.

The sweet (and not so sweet) truth about refined sugar.

The Evidence

Most of you are probably aware that excess refined sugar isn’t great for your health. Sugar and HFCS are particularly detrimental when consumed in liquid form, because we don’t tend to compensate for calories we drink by reducing our calorie consumption elsewhere. (1) This can lead to weight gain from overeating, along with elevated triglycerides, insulin resistance, and other indicators of metabolic syndrome.

Refined sugar has also been implicated in reduced immune system efficiency. (2, 3) In one study, immune cells demonstrated a significantly reduced capacity to kill pathogens (e.g. viruses, bacteria) following sugar consumption (from sucrose, glucose, fructose, honey, or orange juice) when compared with fasting levels; starches didn’t have this effect. Unfortunately, this study was quite small and I haven’t found further evidence to corroborate or refute these results. I believe it’s a good idea to avoid sugar when your immune system is compromised.

Refined sugar is also thought to promote cancer growth by ‘feeding’ the cancer. While it’s true that cancer feeds on sugar, it actually feeds on the glucose in your blood; not necessarily the sugar you eat. (4) While those two factors are obviously linked, it’s more important to be aware of your own blood sugar control, and don’t consume more sugar (or carbs in general) than you can effectively metabolize. After all, you will always have glucose in your blood as long as you’re alive, so the goal is to avoid having high blood glucose over a prolonged period of time, not to eliminate glucose entirely.

But while there’s plenty of evidence that excess sugar or HFCS can be harmful to health, there’s  actually no evidence that small amounts of refined sugar in the context of a nutrient-dense, whole foods diet (and active lifestyle) is harmful. The problem is that limiting yourself to small amounts of sugar is often easier said than done.

Is Sugar Addictive?

Addictive properties of sugar have been observed in rat models where food is restricted for 12 hours, encouraging a binge-like pattern of consumption. (5) These rats experience dopamine and opiod release that resembles the neurological response to substances of abuse, although significantly smaller in magnitude. Additionally, these rats experience opiate-like withdrawal symptoms after being given an opiate-blocker, or after a period of fasting.

Most human studies, however, have not reproduced these findings in rodents. (6, 7) (As always, it’s worth noting that the second reference was partially funded by the World Sugar Research Organization.) At least one small study which interviewed obese individuals did find that, based on self-reported symptoms, some obese patients fit the profile for sugar addiction, particularly those who also suffer from binge eating disorder (BED). (8) But as of yet, there’s little to no rigorous evidence that sugar is chemically addictive in humans.

However, some evidence does indicate that sugar can interfere with the normal hormone signaling from ghrelin and leptin, both of which help control appetite and satiety. (9) So although this isn’t an ‘addiction’ mechanism, it’s another way in which sugar can encourage overconsumption in susceptible individuals.

Whether sugar is addictive or not, from a practical standpoint, it’s often easy to eat more sugar than you mean to. Certain people are going to be far more sensitive to these effects than others, so it’s really a matter of being familiar with your own eating behavior when it comes to potentially addictive foods.

Like what you’re reading? Get my free newsletter, recipes, eBooks, product recommendations, and more!

Is High Fructose Corn Syrup Really Worse Than White Sugar?

So far, I’ve been talking about white sugar and high fructose corn syrup (HFCS) somewhat interchangeably. But HFCS is without a doubt the more vilified of the two, both in the natural health community and in mainstream media. Foods and beverages sweetened with “real sugar” instead of HFCS are seen by many as ‘healthier’ and more ‘natural,’ and even big soft drink companies like Pepsi are trying to cater to the ‘natural’ crowd by offering “made with real sugar” sodas. If HFCS can make sugar look like a health food by comparison, it must be pretty terrible for you, right?

Well, first, let’s talk chemical composition. White sugar, or ‘table sugar,’ is simply sucrose, a disaccharide composed of one glucose molecule and one fructose molecule bonded to each other. This means that table sugar is always 50% glucose and 50% fructose.

Contrary to popular belief, HFCS has about the same amount of fructose as white sugar. It’s also the same level of sweetness. (10) The two most common forms of HFCS in our food supply are HFCS-42, which is 42% fructose, and HFCS-55, which is 55% fructose. This is certainly “high fructose” compared to regular corn syrup, which has no fructose, but most people hear “high fructose” and think ‘mostly fructose,’ which is definitely not the case.

The main difference is that the fructose and glucose in HFCS exist primarily in their free monosaccharide form, instead of as the disaccharide sucrose as in table sugar. And given the similarities between the two sweeteners, it should come as no surprise that HFCS does not have significantly different metabolic effects from sugar. (11, 12)

I know many of you are also concerned about GMOs in HFCS. Genetically modified varieties of both sugarbeets and corn are grown and consumed in the US, with corn much more widely so. (13) Overall I’d say you’re probably better off with table sugar rather than HFCS from a GMO perspective, because it’s produced from crops that are less commonly GMO. It’s also pretty easy to find organic, non-GMO sugar.

So, How “Toxic” Are Sugar and HFCS?

White sugar and HFCS are not “toxins” in the sense that even small amounts are highly undesirable and potentially harmful. Excess refined sugar can have undesirable health effects, but its addictive power is not comparable to a drug, and HFCS isn’t that much different from table sugar. Some people may be highly sensitive to even small amounts of sugar, often due to severe gut dysbiosis, and in this case they’re justified in avoiding it vigilantly.

But barring extreme sensitivity, there’s no evidence to indicate that refined sugar (or HFCS) is actually toxic in moderate amounts, and most people would be better off avoiding the stress that comes from being unnecessarily fearful of any food that has even a trace amount of refined sugar in it.

I’d even go as far to say that intentionally consuming sugar on occasion shouldn’t be a problem for most people. If every now and then you decide to indulge in a piece of dark chocolate or have a scoop of real ice cream made with refined sugar, you shouldn’t mentally and emotionally beat yourself up or force yourself into a week-long “detox” to make up for your dietary transgression. The stress that comes along with excessive food restrictions can be much more harmful than having a bit of refined sugar here and there.

Sugar is neither a toxin nor a replacement for real food. Ultimately, small amounts of sugar can fit into a whole foods, nutrient-dense, healthy diet, as long as you recognize it for what it truly is: a treat.

ADAPT Naturals logo

Better supplementation. Fewer supplements.

Close the nutrient gap to feel and perform your best. 

A daily stack of supplements designed to meet your most critical needs.

Chris Kresser in kitchen
Affiliate Disclosure
This website contains affiliate links, which means Chris may receive a percentage of any product or service you purchase using the links in the articles or advertisements. You will pay the same price for all products and services, and your purchase helps support Chris‘s ongoing research and work. Thanks for your support!


Join the conversation

  1. Most studies of both sugar and HFCS show little to no difference in metabolic and hormonal differences between the two immediately after consumption. However, fructose consumption – which as Chris noted results from both table sugar and HFCS consumption – for as little as two weeks may increase the risk of CVD:



    This may have to with the fact that while CVD has often been associated with type A particulation in LDL, which is saturated-fat stimulated, newer research shows that type B particulation may be the culprit in high LDL numbers – and type B appears to be carbohydrate-stimulated. (I think Chris has mentioned this in earlier posts.) I had a friend years back who had genetic hypercholesterolemia, and she remarked she could eat all the animal fat she wanted, but half a banana sent her LDL number through the roof. That always stuck with me and made me wonder; now we are finding out why.

    All this to say that while Chris is correct in saying that the occasional bit of sugar or even HFCS is not going to kill us, being that CVD is one of the “big three” killers in developed societies like ours, and some of us, like my friend, are more genetically susceptible to the effects of sugars, refined sugars should not be consumed on a regular basis. Besides, we can debate whether beans, dairy, etc. – all things our ancestors ate – are paleo/primal, but refined sugar is simply not one of the things they ate, and should be rarely eaten by those attempting an ancestral diet. Which is pretty much what Chris said – I think.

  2. After 2 years of beeing more-or-less strict paleo I know now for a fact that table sugar is HFCS are not welcome in my body. Every single time I consume any amount of those – my gut tells me “NO”. Palm sugar however seems to be OK. I do get that “sugar rash” feeling a bit but it’s mild and manageable.

    • I’m the same. When I tried coconut sugar it didn’t “hit” my brain in the same way table sugar does, but my body definitely noticed the sugar (and liked it!)

  3. If one is going to use sugar you might as well use sucanat or coconut sugar as they retain some of the nutrients nature has put in there (it may not seem like much but over a lifetime it adds up). In some dishes I realize that it doesn’t work because they have their own flavor, but in something like coconut flour brownies I can’t tell any difference between white sugar and sucanat because of the chocolate.

    I agree with Chris that on occasion sugar is not a big deal. Check the labels not just for sugar but the quantity in products. If sugar adds one gram of carbs then that is hardly a cause for alarm, but in other things like flavored yogurt suddenly there is like 35 grams, then it’s time to pass.

  4. Seems to me I do have a gut dysbiosis because even small amounts of fruit/honey/sugar… just sweet things in general usually leave me wanting more… even berries ans stevia. When UI eat an apple or fig I almost always end up with an urge to eat the whole tree. I don’t experience the same urge with beef, vegetables, fish in general. I can still over eat out of comfort, but it just isn’t the same for me as sweet foods.

    If I’m in a really centered space then it may be possible to eat fruit/sweets, but it can often be the thing that takes me back out of center aside from life stress and relationships, which I’ve used sweets almost all my life to soothe, but unfortunately doesn’t get at the root problem which could be sloppy boundaries causing my stress or repressed emotion making me feel out of center.

  5. I have read in the past that high fructose corn syrup had sometimes contained up to 65% fructose when lab tested for fructose content.

  6. I have a total love-hate relationship to sugar. I avoid it like the plague since I always get sick from it. And when I am in Europe among my family who eats sugar in home baked goods, and also treats of all sorts, I end up going for a taste….and it ALWAYS catches me! To me, I feel out of control once I start eating some sugar containing treats. First day one piece…next day a bit more… etc until I get so sick that I am off my feet, in bed for 3 days. Then I reset my body to zero sugar and only then can I function. I wish I wouldn’t give sugar so much power over me…

    • I’m the same, gitta. I managed 6 months sugar free this year, only to fall of the wagon BIG STYLE. I went on a month long junkfood binge. Luckily I am back on track now and it’s been easier to quit the sugar it this time around. It gets easier with time I think!

  7. My take on plain, white sugar is that it has no real added value in terms of nutrients: no vitamins, no antioxidants, and obviously no fats or proteins. Just a bunch of calories.
    I tend to avoid it. However, if for example I occasionally am lazy and buy a ready sauce for seasoning my BBQ steaks, I won’t go mad if there is “sugar” in the list of ingredients: an apricot has definitely more sugar in it 😉

  8. The best part about avoiding sugar is that you adjust your taste buds. If everything you eat or drink has sugar on it or in it, your taste buds get accustomed to sweetness and you will need more and more of it. Since I stopped using sugar and gave up all grains, I no longer crave sweet food. And foods like raw fruit taste so much better to me. It’s eye opening. Everyone should give it a shot for a few weeks.

  9. I believe everything in moderation! Sugar is hard to not have in our diet, it is in everything. I really try to limit what I have.

  10. Wasn’t the big thing about HFCS that it is metabolized different than sugar? According to Prof Lustig, that it is metabolized like alcohol in the liver and that is the main problem with it.

    • I was also thinking of the talk by Dr. Lustig. It can be found on youtube at https://www.youtube.com/watch?v=dBnniua6-oM

      There are some good points in this post:
      1. for most people a small amount of sugar on an infrequent basis is fine
      2. HFCS in large quantities is more toxic to your liver than regular sugar, because it is metabolized like alcohol

  11. I significantly reduced refined carbs, including sugar in Feb last year. I wanted to reduce inflammation since I was taking myself off Vytorin. I also focused on eating more vegetables and fruit. In November, my hs-CRP was 0.27 (if I recall correctly). My blood pressure went to the normal range and I had lost considerable amount of body fat. Around Christmas time, I “indulged” in some chocolate chip cookies. Since then, I’ve been progressively eating more refined carbs and also seeing my weight start to tick back up. The amazing thing about this is, I’ll tell myself I’m being an idiot when I buy the sugar and flour-filled junk and again when I eat it, but I can’t seem to help myself. I need to reboot and just do what I did when I first started – fast at first then eat grapes, carrots, and other naturally sweet fruits and vegetables when I get the craving. To me, sugar is definitely an addiction. I’ve realized the hard way that just like an alcoholic can’t have “just one drink”, I apparently can’t have “just one cookie”.

    I should note that I am an ex-smoker (two packs a day) and haven’t even had the same response when around cigarettes. Once I even began smoking one cigarette (no idea why) and it didn’t reignite that addiction. I just want to highlight how sugar has more power over me than nicotine.

    • It is important to remember in these types of discussions that we are all different. Different people have different metabolisms, sensitivities, predispositions to addiction, and reactions to foods. I definitely think there is no one true answer, it depends so much on the individual’s body systems and reactions to specific foods. I think we can all agree that excessive sugars are bad for us, but getting down to the nitty gritty of how much is acceptable will vary from person to person.

    • same, ex-smoker can smoke once in a while… but SUGAR (sucrose!)… is WORSE… eating it again… one ice cream (chocolate or coconut or vanilla, you name it) and I have to get a 2nd or even 3rd serving…
      And then I CRAVE something really sweet, ideally ice cream after every meal, no matter how satiated I am!
      It then takes strong will and 3-7 days ZERO sugary desserts/treats… and the craving addiction is broken again…
      Until the next occasion, being invited, etc. this “evil” cycle starts all over.
      Going over most of the comments here, there are far too many people, that have the same “addiction” problem… that your article Chris, should have ended with the comment/warning, you gave further down, for people like us… NO! SUGAR is the only solution and trying to get rid of really all “sweet” tasting processed stuff, if you fall in that camp!
      The problem, you only know it when it’s often too late.
      Many can not quite sugar without outside help, because their bodies are simply incapable of riding themselves.
      “Moderation” is for these the worst advice, and I’m sure that was not your intention! However the result, when reading only your article, lacking your above mentioned comment, is RISKY!
      So bottom-line… man made SUGAR is a very dangerous substance with a very high “addictive” craving potential and for some even worse then nicotine!
      And in nature the ideal glucose/fructose (most fruits, etc.) ratio = 2:1 compare that to 1:1 and worse even HFCS was found… with up-to (undisclosed) 1:9 = 90% fructose!
      God/Nature knows why wild/raw honey, combining all the many different sugars in it, has that overall 2:1 ratio and only fools compare organic raw honey to man made sugar or HFCS.
      They are night and day apart! incl. how they are assimilated and metabolized in our bodies! And all cane, etc and syrups, incl. even praised maple/palm syrup are almost as detrimental as table sugar is, with hardly any noteworthy vital substances they provide!
      So if something sweet is a “must” for you, then other than fruit, even dried… raw organic honey is the healthiest choice, specifically honeydew varieties, some of these are even “prescribed” in 1st world countries as early treatment for diabetics and they have worked for centuries as cure!!
      Try that with SUGAR, syrups or HFCS?!

  12. I agree with Chris, that sugar in small doses is not toxic. Nevertheless I do avoid it as much as I can, because as soon as I eat a little, I start craving more. What little sugar I eat I ingest in the form of fresh fruit, honey, or wine. Occasional dark chocolate is welcome. As long as I eat some potatoes or rice, I don’t crave sweets. The starch is preventing sugar cravings in my case.

      • While I agree that moderate consumption shouldnt be a big problem I think that if you dont define what ” moderate” means this becomes an exuse for some to go back to bad habits. Psychologically its easier to stop eating something completely than to consume it in moderation. I only have one bite now and again ro humor people. Happy to have that demon behind me.

      • I am surprised that nobody on this thread, including you Chris, has raised the alternative of eating cheese (can you say “triple cream”) for dessert or a treat.

        It certainly works for the French, and my family’s experience is that it works for us. We eat our cheese with a spoon or fork (and yes, usually wine) – no need for bread.. Maybe we’re outliers, but I challenge folks to try it.

  13. I have cut way back in sugar after learning that my mom is type 2 diabetic. I am obese and trying to regain my health before I get like her. She is 74 (today) and still a sugar addict even though I control most of what she eats she takes any chance she gets to eat sugar and doesn’t like any unsweetened foods. I let her have xylitol in her coffee and I make ice cream sweetened with a little xylitol and fruit like berries. She goes to the senior center and brings home snickers bars, ugh! Anyway, at least in my family sugar is an addictive substance.
    I do buy evaporated cane juice for making kombucha. But that is all I use it for.

    Btw, azurestandard.com has birch xylitol.

  14. I did not realize that “the main difference is that the fructose and glucose in HFCS exist primarily in their free monosaccharide form, instead of as the disaccharide sucrose as in table sugar”….. Question: Is this significant? Does the table sugar stay in disaccharide form even when dissolved in food? How about during the digestion process? I assume it converts to glucose and fructose at some point, correct?

  15. As a Type II Diabetic, I try to stimulate insulin production as little as possible, so I limit sugar. A question, however: the fructose or glucose in HFCS Is still fructose or glucose, so what chemicals are different in GMO vs. non-GMO HFCS? Has that science been done?

  16. Chris, Even though “cane” sugar isn’t GMO per se – isn’t it sprayed with Glyphosate during it’s growing season????

    • I don’t think any non-GMO plant can be sprayed with RoundUp and not die. That is the point of GMO, it’s resistant to RU which is a non-selective herbicide. I just googled and while they are developing GMO sugar cane (of course they are) it’s not widely used yet. So your best bet would be organic sugar.

      But honestly, unless you are a professional baker, you can use raw organic sugar and just avoid any possible GMO.

      • There’s another reason for developing GMO crops…..profit. If you can convince farmers that GMO crops will diminish their need for herbicides and pesticides they will flock to your product. And once they start using it they’re pretty much locked into it.

        Also, Monsanto for one, has aggressively pursued the protection of their GMO seeds…even when their GMO crop pollen has contaminated a naturally produced seed crop. Some years ago there was a high profile case in Canada where a farmer who had spent years developing his own brand of soy was sued by Monsanto after his crop was contaminated by GMO soy another farmer was using. Monsanto won the case.

  17. I find soda pop to be pretty disgusting most of the time, except on a hot summer’s day when I’m engaged in some extended outdoor activity: hiking, cycling, etc… then I crave it, though even then a whole 12 oz can seems a bit much.

  18. I avoided sucrose for about five years, never did me much good, a couple of years ago I came across Ray Peats work and after reading his references I started checking Paleo type dietary claims more closely.
    I think Peat is correct, there is not strong evidence that sucrose causes disease. Peat’s recommendation however is to get sucrose/glucose/fructose from non-starchy fruits, the major difference being the alkaline minerals.
    I have seen my health massively improve from increasing fruit intake, calcium, gelatin, and avoiding PUFA etc.

    The rodent study mentioned in the article is bordering on the comical;

    “Addictive properties of sugar have been observed in rat models where food is restricted for 12 hours, encouraging a binge-like pattern of consumption.”

    Am I to believe that pathological behaviour in mammals with a high metabolic rate that have been starved is due to “sugar addiction” ? Could we cut their legs off and claim that their impaired mobility is due to “sugar addiction” also ?

    HFCS is a different beast altogether, aside from the mercury “the carbohydrate contents of (HFCS) beverages determined after acid hydrolysis were substantially (4–5 fold) higher than the listed values of carbohydrates. ”

    I’d urge everyone to read the articles and references on Ray Peats website.