Are You Lower-Carb Than You Think? - A Case Study | Chris Kresser
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Are You Lower-Carb Than You Think?

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how low is low carb
Fruits like blueberries, are a good option for a low carb diet. istock.com/BrianAJackson

We’ve talked before about the benefits and risks of low-carb and very low-carb diets. Laura, one of my staff nutritionists, wrote an article called “Is a Low-Carb Diet Ruining Your Health?”, and I followed up with an article called “7 Things Everyone Should Know About Low-Carb Diets.” Then Kelsey, my other staff nutritionist, wrote an article called “The 3-Step Process for Determining Your Ideal Carbohydrate Intake.”

Are you on an “accidental” very low-carb diet? Find out here:

The takeaway from all of these articles is relatively simple and uncontroversial—at least according to anthropological and clinical research:

  • Very low-carb (VLC) and ketogenic diets are useful therapeutic tools in certain conditions.
  • Some (but not all) people experience adverse effects from following VLC and ketogenic diets—especially when done over an extended period of time.
  • Very low-carb diets were extremely rare during the course of our evolution and are not the “default human diet” (as some have claimed).

Now, I want to address an issue that I see relatively frequently in my private practice. I’ve begun to think of it as the “accidental low-carb diet” phenomenon. The best way to explain this is to share a case study. 

The Accidental Low-Carb Diet: Frank’s Story

A few months ago I spoke to a patient—we’ll call him Frank. Frank is a 32-year old male who is on the SWAT team in a major metropolitan city. He came to see me complaining of extreme fatigue, insomnia, and exercise intolerance. These issues were obviously of paramount importance given his job.

About a year prior to our first visit Frank had started a low-carb Paleo diet. Some of his colleagues on the SWAT team were doing it with great results, so he figured he’d give it a try. He wanted to lean out and lose about 5 pounds of belly fat that he was having trouble getting rid of. After a few months on the low-carb Paleo diet, Frank did reach his target weight and body composition. 

But then the fatigue and insomnia started. A few months after that, he noticed he was having trouble keeping up with his training routine (which is, as you might imagine given his profession, quite rigorous). 

Frank reads my blog and listens to my podcast, and he had heard me say that some people can experience problems on a very low-carb diets. So he started to add some carbs back into his diet. This helped a little bit, but when he finally set up an appointment with me he was still struggling. 

When I talked to Frank, I asked him how he would characterize his diet. He said he used to do low-carb, but now he was on a moderate carb. I’ve learned over time not to accept this at face value, so I probed further. I asked him specifically how much carbohydrate he eats in the form of starchy plants and fruit (more on this below) on a daily basis. His answer: a sweet potato and about a half a cup of blueberries 3-4 times a week.

Although Frank thought he was on a moderate carbohydrate diet, when we did the math, it became clear he was on a very low-carb diet with fewer than 10% of calories from carbohydrate. Here’s how it breaks down:

  • Frank is 6’3 and 215 pounds (with a lot of muscle). He is extremely active. In order to simply maintain his weight, he would need to eat about 3,000 calories a day.
  • If we define a moderate carbohydrate diet as 25% of calories from carbohydrate, that means Frank would need to eat 750 calories a day as carbohydrate. At 4 calories per gram of carbohydrate, that comes out to about 188 grams of carb each day, or 1,316 per week.
  • A large sweet potato contains 37 grams of carbohydrate. 1/2 cup of blueberries contains about 10.5 grams of carbohydrate. In addition to these amounts of starch and fruit, Frank ate about 3-4 servings of nonstarchy vegetables each day (about 25 grams of carbohydrate on average). Given these numbers, Frank was eating about 365 grams of carbohydrate a week.

At 3,000 calories a day, this works out to about 7% of total calories from carbohydrate. That is most certainly not a moderate carbohydrate diet.

Do Carbs Cause Weight Gain? Frank’s Experience.

When I explained all of this to Frank at our appointment, he was pretty shocked. He was under the impression that eating a few sweet potatoes and some berries throughout the week put him in the “moderate carb” category. Obviously, this was not the case given his weight and activity level.

He was even more shocked when we calculated how much carbohydrate (again, from starchy plants and fruit) he’d have to eat to get to the “moderate” carbohydrate level of 25% of total calories. For Frank, to reach this target of 188 grams per day, he could eat the following:

  • Four servings of nonstarchy vegetables (25 grams)
  • One large Russet potato (64 grams)
  • One cup sliced cooked plantain (48 grams)
  • One medium banana (27 grams)
  • One cup of strawberries, halved (12 grams)
  • One half-cup of blueberries (11 grams)

This meant having a full serving of a starchy plant with two meals, and some fruit either with each meal or between meals—far more carbohydrate than Frank was eating previously.

Frank was initially reluctant to eat this much carbohydrate. He told me that he had noticed that carbs caused him to gain weight. But again, when we I dug a little deeper it became less clear that it was carbohydrate in general that caused weight gain, but a certain kind of carbohydrate (namely, processed and refined carbs). 

Turns out that Frank had very strong cravings for carbohydrate after a while on the VLC diet. Instead of increasing his intake of starchy plants and fruit, he’s stay extremely low-carb and then fall off the wagon by eating bread, pizza, or something like that. Not surprisingly, he would gain weight after these “indiscretions”. (Interestingly enough, he would also feel more energetic and sleep better afterwards.)

I asked Frank whether he gains weight when he eats carbs from whole-food, Paleo-friendly sources like starchy plants and fruit. He said he didn’t know, because he had never tried eating the quantities of these foods that I was recommending. So of course that became our next experiment. 

When I spoke to Frank about ten weeks later, he was ecstatic. His insomnia was completely resolved. His energy levels were not only restored, but higher than they’d been in recent memory. But what he was happiest about was his increased performance at work; Frank had recently placed highly in a national SWAT competition that his team competed in. 

What’s more, he accomplished all of this without gaining a single pound. On the contrary, he had lost a further 3 pounds of fat and was more “lean and ripped” than he had been on the VLC diet. 

If this had been an isolated experience with a single patient, I wouldn’t even bother writing this article. But in fact it’s a fairly common occurrence in my practice. I have every patient I see fill out a diet diary which shows me exactly what they eat on an average day. Then I ask them what their carbohydrate intake is like. I’d say about 50% of the time—if not more—my patients are consuming significantly less carbohydrate than they think they are

If you think you might fall into this category, you can use the guidelines below to calculate your optimal carbohydrate intake. 

How to Calculate Your Carbohydrate Intake

The first important thing to understand is that it’s far more useful to think in terms of of percentage of calories for carbohydrate than it is to think in terms of grams per day. I often hear people make recommendations for the number of grams of carbohydrate someone should eat. But this is meaningless when you don’t take weight and activity level into account. 75 grams a day may be a moderate-carb diet for a sedentary woman eating 1,600 calories a day, but it would be a very low-carb diet for a highly active male eating 3,000 calories a day. 

The table below illustrates the ranges for “very low carb”, “low carb”, “moderate carb”, and “high carb” using percentage of calories for carbohydrate. I’ve also included examples for how many grams of carbohydrate an average, moderately active male and female might consume per day given those ranges, as well as a list of health conditions/goals that might do well for each range.

Carbbohydrate Intake Chart

In order to calculate your exact target range, follow these steps:

  1. Figure out how many calories you should eat per day. This depends on your height, weight, activity level, and goal (weight loss, maintenance, or gain). You can use any number of online calculators to get this information.
  2. Once you have your daily calorie intake, multiply that number by your target percentage of carbohydrate. So, if your daily calorie target is 2,000 calories and your target carb intake is 20%, multiply 2,000 by 0.2.
  3. Once you have the number of calories per day from carbohydrate you need to eat (from step 2 above), divide that by 4 to obtain the number of grams of carbohydrate you should eat. In this example, you’d divide 400 calories by 4 to get 100 grams. That is the number of grams of carbs you need to eat each day.
  4. With this number in mind, you can then consult the charts below, or use online tools like NutritionData.com, to figure out which foods you can eat to meet your goals.

If you’ve never done this before, I’d encourage you to give it a try. If you’re like many of my patients, you might be surprised to learn that you’re eating a lot less carbohydrate than you thought.

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Carbohydrate-Content-of-Selected-Fruits

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206 Comments

Join the conversation

  1. If I (49 years old female, celiac (silent, brain type) very light activity, almost sedentary) increases carbs form a ketogenic diet, should I increase protein or fat, decrease protein or fat? Not sure how to precede but very interested in adding carbs. Any advice, I am grateful.

  2. Hey, what about our beloved buckwheat? Seems that should be considered a good source of carbs no? Nutritionself.com says 1 cup of roasted has 33.5 carbs (29 without fiber). And wouldn’t sprouted have more that’s bioavailable?

    Someone also mentioned legumes (cooked in the careful way of course!, ie soaked and sprouted).

  3. I have been following the recent Carb articles and really appreciate this detailed information! I have one question that I haven’t seen addressed, and it comes up a lot in my practice…are we looking strictly at total carbs, or total sugars? How much do we take into account foods (like unsweetened cacao) which have carbs but low or no sugars? Thank you!

  4. I ate a VLC diet for several years, experienced the same symptoms mentioned above with low energy, insomnia and inability to recover from exercise. Whenever I added some carbs back I put on “weight” instantly. It turns out it’s gut dysbiosis and SIBO that I was controlling with the VLC diet. Adding carbs back and getting treatment for SIBO has helped tremendously. I feel so much better!

  5. Hi Chris,

    I have been trying to lose weight for over a year now and I cannot go under 140…. I tried a juice diet to help me with the elimination diet and lost 13lbs but then I started to gain weight so I tried to count my calories, then I reduce my carb intake, my sugar intake but I kept gaining weight and now I’m back to 140 and whatever I do it stays there. I suspect that I have thyroid problems because I have a low libido, I lost my hair due tu remicade but maybe my thyroid made it worse, I also had my period a week before to stop my pill for the past months. I don’t really know what to do should I increase my carb intake or lower it? I also exercise everyday I alternate power walks and strength training everyday and on Sunday I take rest.

    Help, please!

  6. I absolutely love this kind of information! I tried the paleo diet and wound up with heel pain. I am now eating vegetarian and feeling no pain in my heels. It took a few months to get rid of the pain.

    I need to figure out how many carbs I need to get in a day but with this info I will know how to figure that one out!

    Thanks!

  7. Very interesting and may explain my fatigue every afternoon. I eat 40 to 60 gms carb per day: no grains, no starches, no dairy, almost no fruit. Finally succeeded in getting prediabtes under control..A1C now 5.5 and LDL 125 (yay!). Do I dare add in carbs? Won’t this mess up my blood sugar control which took me a few years of low carb diet to achieve?

  8. I made this mistake. I was counting weight in grams of the starchy veg/fruit etc not the actual carb content.

    I am now using MyFitnessPal to log my carbs, but I have to admit I’m finding it hard to hit target.

    And eating more carbs means less protein and veg which takes some adjustment.

  9. Great article – but the link you post for an online calculator doesn’t allow for inputting exercise, and suggested a caloric intake frighteningly below anything you would recommend (1200-1400 calories a day for a 5’9″ woman in her early 30s?!).

    • I found the same calorie calculator to be very frightening! I am a 5′ 9″, moderately active woman with a high muscle mass – it recommended 1350 – 1550 calories per day for me to lose weight which is below my basal metabolic rate.
      Can anyone recommend an accurate calorie calculator in which the user can choose lifestyle + exercise frequency?

  10. THANK YOU for this article. This information was very timely. I’ve been plateaued in my weight-loss adventure for the last 3 months (frustrating!). Like others on this site I kept upping my fat to lose weight and it wasn’t working. I’ve also had a lot of trouble sleeping.

    Looks like Chris Kresser once again came to the rescue. I’m not eating enough carbs!!! Thoroughly enjoyed adding some potato to my bacon and eggs breakfast this am.

    I would have said I was medium carb, too, but appear to actually been eating VLC!

  11. Hi Chris, awesome article, explains a lot and mirrors the symptoms I’ve been having.

    I initially tried keto 2 years ago and have been on it 90% of the time. For me it was for weight loss and it worked.

    For everyone out there who might read this, Chris I agree and can’t thank you enough for previous articles on this… It really is personal about how you feel and cope on keto diets.

    I have been playing around with the amount of carbs, and for a long time I strived to be under 20 grams per day, and felt brilliant on it. I lost 10 KGS, told everyone about it, refused to go over my ‘carb limit’, then one day just crashed. Same symptoms as ‘Frank’ no energy, no appetite, and struggled even with mental lethargy as well as physical. The one thing for me when I know I’ve been too low for too long is nausea, and I’ve found simple things help massively. Even a single piece of fruit or a mochachino helps with the energy levels a lot.

    It really is an experiment for everyone, but even though I thought I was being careful and doing the right thing, I was often going too low carb and feeling rubbish as a result.

    Funnily enough one symptom people don’t talk about : when I go too low carb, and I’m just about to crash, I don’t necessarily crave carbs, but I feel emotionally drained and down. Does anyone else get this? I’ve learned that for me it’s one of the triggers, that I can watch out for quite easily. (Or I ask my wife if I’ve been more of a pain in the are than usual (that’s normally a yes!)

    Of I add a portion of starchy veg to my meals in the evening, I feel like I’ve been good all day and the small amount of carbs resolves all my symptoms really quickly, but more than that – it actually make me happier! Just wondering if anyone else had experienced this?

    • I can relate to your experience exactly as you state. For me its a mental, somewhat depressive feeling, and although I feel great 90% of the time on low carb, I know I can lift my mood with a sweet potato from time to time.

  12. Thank you, Chris! I’ve been looking for a chart like this. Very cool to see sweet potatoes coming in at 37g vs. white potatoes at 64g. Seeing concrete info like this is awesome. Super helpful!!

  13. Thank you so much for this I am currently breastfeeding and have 3 very active children until I read this and did the calculations I realised I am not eating near enough carbs! I get very tired in the afternoon and after dinner I crave bread and other bad refined carbs and often end up over indulging and feeling terrible the next day. I am overweight from my pregnancy and would like to lose weight but do not want to affect my milk supply. I am very busy and often need to pre prepare my meals otherwise I end up skipping meals or eating too late. I will be very interested to see the change when I try to eat the amount of carbs per day I am meant to be eating. Hopefully I see a change in my energy levels and less cravings !?? Thank you

  14. Thank you so much for these articles Chris!! I, like many others was accidentally eating too few carbs, for way too long!

  15. When I did this calculation, I was eating less than I thought. I added some legumes (about 3-4 servings a week) and it helped a lot. My meals now last me several hours.

  16. Hey Chris,

    I noticed that you might — depending on other factors as well — recommend a lower carb diet for someone with mood disturbances. Can you elaborate a little on this?

    I think that popular opinion is carbs increase mood, yet I definitely notice I’m edgier when I have more carbohydrate in my diet, so this caught my eye.

    Thanks,
    Stu

    • As is often the case, it depends on the patient and the cause of the mood disturbance. In some cases, VLC helps. In others, boosting carbs helps.

  17. Great article! This really resonated with me. Several years ago, I started having unexplained periods of exercise intolerance. Since exercise intolerance is often associated with a failing heart or heart disease, I was concerned, to say the least. Stress made this condition worse. I have become more and more convinced that this is due to a carbohydrate deficiency. Who knew. I have come to Paleo from the low-carb community and this is something that is still not readily accepted.

    How this brings up an important question. Do you have any advice for people who have blood sugar issues and who might be diabetic or pre-diabetic but do not do well on low-carb.

  18. “Very low-carb diets were extremely rare during the course of our evolution and are not the “default human diet” (as some have claimed).”

    HUH!!!??? WHA’!!!???

    Frankly, Europeans MUST have experienced extended very-low-carb periods during their evolution, because of both harsh winters and the last ice-age, which occurred during the upper paleolithic, from approximately 110,000 to 12,000 years ago. Humans were there during that whole time! And so I can’t imagine how you can possibly say that!!??

      • Homo Sapiens… with basically the unchanged (or only moderately changed) DNA, that paleo adherents like to point out, have only been around for 200,000ish years. Earlier than that were not Sapiens and so, by definition, had a different DNA (and diet). This has always been a point of contention with me. :-/

        So, I stand by my statement.

      • I guess the homo sapiens that came from more equatorial regions would be different again i.e. eating more starch than their northern co-species.

        • One of my ancestresses was still living in Africa 50,000 years ago as my maternal haplotype is L1b and that’s when this mutation occurred. Most people in the world with this haplotype are living in around Nigeria.

  19. I can relate. Low-carb paleo has thrown my thyroid out of whack. I am on 60 mg of Armour to get my TSH down from 9.0. Also have low T and high LDL.

    Any thoughts on beans? I really enjoy them and the ease of a can of beans, refried, chili or properly soaked and cooked beans are my go to vs. taters and rice. Any issues with them as a carb source that seems to stick to my bones more (i.e. doesn’t elevate my blood sugar and leave me hungry a few hours later)

  20. After several years of success on paleo but still being ~20 lbs from my goal weight of 140 (the high end of being healthy for my height of 5′ 3″), I decided to go low carb paleo. Spent about 4 months at about 25 g carb/day, with occasional treat meals. Low-carb, compounded with professional stressors have given me about 6 months of insomnia. It’s like my head hits the pillow and suddenly I am awake. I have gone 48 hrs without sleep on many occasions. My friend’s mom, who works in naturopathy, said it sounded like adrenal fatigue. I’m trying to add carbs back in. I’m doing a banana and either white potato or sweet potato towards the end of the day, because I find I sleep better if I carb-load towards the end of the day. I sleep like a baby after occasional servings of white rice…not exactly paleo, though! Is there any recommendation for optimal times to consume carbs?

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