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. I find when I eat a moderate carb diet, I get a sore throat at night. It’s mild, but aggravating. I also get gas. Very low carb, have plenty of energy and feel better.

    • See, this, to me, shows the detrimental effects your diet is having on you.

      1.) If you’re waking up with a sore throat, I’d estimate your body is overproducing hystamine and the result is sinus congestion and a post-nasal drip. Your diet has probably wiped out your gut of healthy bacteria, so this is indicative of a body susceptible to autoimmune conditions. Your diet void of healthy, soluble carbohydrate probably has you extremely prone to allergies.
      2.) You get gassy because your gut bacteria is probably severely disregulated. You lack the healthy bacteria that lets you ferment carbohydrate, so you have digestive issues.
      3.) You probably feel better and less tired not eating carbohydrate because you’re extremely insulin resistant and likely exhibit diabetic-like symptoms. A diet rich in carbohydrate makes you insulin sensitive. You probably have a physiological condition very similar to type 2 diabetes.

      All these things would likely be solved if you just ate carbs and stuck with it.

      • OH MY GOSH! This is me to a tee! Funny thing is that my Endocrinology Dr. who treats my hypothyroidism and borderline diabetes, has been telling me for years to cut out gluten, processed foods and sugar. So 4 mos. ago I finally did for fear of being put on yet another medication and felt better then I had in years, but I think I took it too far cuz now I don’t feel so good anymore. In my case, I don’t think I’m eating enough calories yet I’m still fat! I hate feeling like I can’t eat anything anymore in fear of the consequences. Thank you for your comments they had been very enlightening and helpful. My recent bloodwork came back with my LDL-P number at 1950 so she wanted to put me on Statins STAT!!! Funny but not funny! I said no, and am doing large doses of fish oil and red rice yeast. Hoping for the best…

  2. Chris:
    Excellent Article! I went on a Ketogenic diet. After 5 weeks my blood pressure spiked and I had to add more Carbohydrates, which helped. Now my energy level has dropped so I will gradually increase my Carbohydrates as you have discussed in this article. Keep up the good work!

  3. As a Type 1 diabetic I have been following Dr Bernstein’s diet (30 grams of non starchy veggies per day) for 7 years which reduced my HA1C to 5.6. In that time I have developed fatigue, low thyroid, high LDL, adrenal dysfunction (low cortisol am, high cortisol pm) and insomnia. 9 months ago I added 20 grams of carbs per day from fruit and/or starchy veggies. HA1C came up to 6.0, LDL is almost normal, TSH is normal but fatigue and insomnia remain the same. It’s tough to figure out what to do, I am still considered VLC by this chart but afraid to add more. I can cover more carbs with insulin but more carbs/insulin equals more variation in blood sugar, I take 14-16 units daily. Any recommendations? Thank you….

  4. It appears that you treat a lot of diseases but you don’t seem to mention cancer. Is this due to legal/liability reasons? You mentions a lot of other chronic diseases so I am curious. Your low carb articles have really peaked my curiosity. While I am now cancer free, I am being advised to maintain a low carb (25g to 50 g depending on doctor/naturopath). I would love your opinion regarding cancer and carbohydrates in your diet.

  5. Hi Chris,

    I’m increasingly a believer in food being the best medicine (and vice versa), and am trying to figure out some gut issues. Think stress from starting a business and planning a wedding while husband went back to school spiraled me into regular diahrrea a couple years back, not helped by an irregular diet and too much wine. Currently going through a battery of tests with GI doc (blood work and abdominal CT scan were normal last week), colonoscopy tomorrow. Reading this article makes me realize that I’m really not eating many carbs. Do you think an extreme lack of carbs could be causing/contributing to my issue?

    Many thanks. Big fan 🙂 Angela

  6. I am just wondering how increasing carbs can be done with sibo?
    I have all the symptoms of a vlc diet- insomnia, lack of energy etc, but struggle worse every time I add in carbs?

  7. My daughter is a highschool swimmer who swims about 11000 yards/day. She was on a ketogenic diet for about half a year and it did get her out of the pre-diabetic range, but her swimming performance suffered. She is now adding some potato salad (resistant starch), green bananas, tomatoes and some more fruit to her diet and her energy has increased a lot. No more bonking and times for 100 freestyle improved by 5 seconds in one week. I’m hoping her blood sugar won’t go up too far again. We are also considering adding super starch (slow-release carb).

  8. Hi Chris,

    Great article! I am wondering what a good starting point would be for me if I am a mix of categories. I am very active (running and weight training 6 days a week), which would put me around 25% but I also want to lose body fat so that would put me around 15%. I’ve had other macro calculations suggest 40% carbs and then 30% protein and fat. It’s all very confusing!!

  9. I had the same experience as the man in the article. I’m female, 42, Hashimoto’s. My version of low carb was trying to stay around 75 g/day. And boy, did I feel like crap. Totally exhausted — and the insomnia! I started adding some rice or potato with dinner, and my energy rebounded instantly, as did my sleep. I firmly believe Chris on this issue. No fast weight loss is worth feeling like that.

  10. It took about a year of paleo for me to handle 25-30% of carbs and -before- even fruit disrupted my blood sugar. Then after a year of paleo and lots of probiotics I handle paleo carbs 25-30% very well now and enjoy them more too.

  11. All this talk about too low carbs might be okay for the average person but some like myself have to have low fat & low carbs… I have Hashimoto’s and my body doesn’t metabolise carb or fat very well.. in fact it stores both at the drop of a hst. There is way too much carb in our western diet if you ask me. After 20 years with this condition I am the same weight as I was at 34 ( though the sand has shifted a little due to being in my 50’s now). If you ask me everybody would be better off with alot less carb-especially to svoid Type 2 diabetes-the next scourge of our society as a result of obsession with too much food!!

  12. Hi,
    I have been following a low carb primal/paleo diet for over a year and initially lost weight, I have been gluten free for 3. I carry my fat in the middle…I have about 20-30 pounds to lose, according to my bmi. I run about 12-18 miles per week and lift weights 3x per week. I also do HIIT training in addition on a treadmill. I am a female, 37 years old, hypothyroid and some hormonal imbalances (pcos, fibroids)and have not lost weight in a year. There is no evidence of adrenal fatigue. My doctor suggested that I change my macronutrients to 40/30/30 with carbohydrate being 40. I am currently tracking this with my fitness pal and weighing everything. I am getting close to those ratios about 50F/25/25. I would really like this weight to come off. What do you think?

  13. It seems many people are associating their ailments or fixes to carbs. Be careful these are just associations. For weight loss which is the number one problem in the Western world stay under 30g of carbs per day. Also very important is to eat heaps of fat and moderate protein. I suggest your client was not eating enough fat.

  14. Louise,

    I eat 25-30-40 grams of carbs daily.

    Are you taking in enough salt? How is your water intake? I love a glass of salt water (make it myself) with the juice of one lemon. Helps immensely with any sight fatigue in mid-afternoon. Often a 10 minute nap is all that is called for too.

    Everyone on low-carb needs salt! Very commonly addressed in the research and literature.

    • Yes agree with salt issue. Stephen Phinney discusses this. Need to have 1-2 cups of broth. I add nice pink salt to all my food. Love it

    • Anne and Alien,
      Thanks for the salt idea.. I haven’t been restricting it .. I eat very little of processed foods, but use the salt shaker at the table. Maybe I could add more salt, as it’s worth a try. I also eat bone broth, about 1/2 cup per day.
      I also struggle with GERD, so would need to try out the lemon idea and hope for no reflux from it.

  15. Hi Chris,

    How might I decide my optimal carb percentage if I am a type 1 diabetic, taking Synthroid for thyroid support due to off the charts antibodies, and I’m exclusively breast feeding an 8 week old baby!

    The type 1 diabetes and desire to lose baby weight requires a lower carb intake, but the breast feeding and thyroid issues require more.

    Thanks for your insight!
    Kori

  16. Hi Chris,

    For someone with a mix of issues which carb category should be chosen? I have less than 5 pounds to lose to be in the upper end of the healthy range for my height. And, I have PCOS, Hashimoto’s, hypothyroidism and a tendency for hypoglycemia. I’ve been gluten free for more than a year and am roughy following an autoimmune paleo protocol (with the addition of nuts I can tolerate). Going to a new doctor at the end of October but was hoping to hear your advice prior to if possible. Thanks!

  17. Hi Chris.
    Great article, and it’s made me realise I am not eating enough carbs. I’m 27 male, 220lb and train 4-5x a week as a sprinter.
    I’m also suffering low cortisol as from years of excessive training.
    I struggle to get in enough carbs in a day, so what are your thoughts on using dextrose powder to get my carb count up? Obviously timed around training?

    Cheers

  18. This article describes my last year perfectly. I thought
    I was doing everything right and I couldn’t understand why I was getting more and more hypothyroid. I had heard that more carbohydrate might be the key but I guess I was being stubborn about it until I started reading this series of articles.

    Just started adding carbohydrate back about two weeks ago. I’ll let you know how my numbers look in a few weeks

  19. It seems I only get about 10g of carbs a day. I had no idea it was so low. Based on the numbers above I really need to add some carbs to my food routine. I don’t do it on purpose, I just don’t enjoy carbs much. I’ll be curious if it helps with my mild fatigue.

  20. Thank you! That would have to be the single most informative article I have ever read to help me understand carbs on a paleo style diet.

    I have struggled with exhaustion and brain fog and just haven’t been able to shift the last few kilos for some time now and I think with your help I just figured out why.

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