The Hidden Dangers Of A Low Carbohydrate Diet

If you're a frequent visitor to this website, or listener to the BenGreenfieldFitness podcast, you've probably gotten the idea that I'm a pretty big fan of limiting your carbohydrate intake.

And you'd be right.

To understand why low carbohydrate eating can bestow some significant health and performance advantages, check out my Perfect Health Diet interview with Paul Jaminet, or listen to the perils of constantly elevated blood sugar levels in this episode with Nancy Appleton: Which Foods Contain Hidden Sugar That You Didn’t Even Know About.

Or go read about how physically active individuals may be able to actually benefit from strategic low carbohydrate intake in my article 4 Reasons To Think Twice About Eating Carbohydrates Before A Workout or (if you're a Rock Star Triathlete Academy member) you can read 5 Ways to Get A Big Carbohydrate Restricting Performance Advantage.

In a nutshell, pun intended, as you begin to increase carbohydrate consumption above the levels that you need for survival or periods of intense physical activity, you lose your ability to rely on fat burning mechanisms, and you experience the damaging effects of chronically elevated blood sugars, including neuropathy (nerve damage), nephropathy (kidney damage), retinnopathy (eye damage), increased cardiovascular disease risk, potential for cancer progression (tumor cells feed on sugar) and bacterial or fungal infection.

Unfortunately, whether due to a misinterpretation of what low carbohydrate dieting actually is or an “all-or-nothing” approach to restricting carbohydrates or perhaps the influence of low-carbohydrate-done-wrong diets like Atkins, many people (and especially athletes) try or attempt to try a low carbohydrate diet and end up messing the whole thing up, experiencing the hidden dangers of a low carbohydrate diet and hurting their bodies.

So what are the hidden dangers of a low carbohydrate (AKA “ketogenic”) diet?

Here are the low carbohydrate risks, in ten steps:

1. Your body stores carbohydrate, mostly in your liver and muscles, in the form of glycogen. Depending on your size, you can store roughly in the range of 1500-2000 calories of storage carbohydrate (although that number is fairly variable based on your fitness and size).

2. If you're sedentary and don't really exercise much (which I don't encourage), this amount of storage carbohydrate is more than sufficient to get you through a typical day. Really, your body only needs a maximum of 600 calories of carbohydrate to survive each day – and that carbohydrate can be derived from diet, or from you own storage glycogen.

3. But if you're active and at the same time consuming a low carbohydrate diet, you can easily burn through your liver and muscle glycogen stores in anywhere from 2 days to a couple weeks. The nice part about this, if you're trying to lose weight, is that since glycogen carries up to four times it's weight in water, a low carbohydrate diet can quickly shed 5-10 pounds (or more), which seems quite satisfactory. But the problem is, most of what you've lost is A) energy to sustain intense physical activity and B) water.

4. So now you have very little storage carbohydrate and are potentially dehydrated. If you're an athlete or a physically active individual, this means that you're limited to utilizing fat as a fuel for energy. Fat, through a process called “beta-oxidation”, can provide tens of thousands of calories of readily utilizable fuel, but the problem is that it burns far more slowly than carbohydrate.

5. This means that if you're on a strict low carbohydrate diet, you can say goodbye to intense weight training, track intervals, or just about any activity that would be consider “tempo”, “threshold”, or “intervals”. And this is the stuff that adds lean muscle to your body, boosts your metabolism and gets you fit fast – compared to a slow and sluggish slog in your “fat-burning zone”. This is not negotiable by your body. It is simple physiology. When you deplete muscle glycogen, there is a directly proportional increase in muscle fatigue, and also an increase in muscle catabolism (direct metabolism of your body's own muscle protein, or conversion of that protein into glucose via gluconeogenesis). Many people on a low-carbohydrate diet simply stop exercising, because it can suck so much.

6. As you lose muscle mass, your already handicapped metabolism drops even more. I will acknowledge that muscle fibers don't burn as many calories or boost your metabolism as much as we all like to think, but this is still an important consideration for those trying to maintain lean muscle mass or tone.

7. For active people, this trouble may all be “in vain”. Since physically active individuals and athletes are far more sensitive to insulin and less susceptible to blood sugar fluctuations, any attempt to eat low carbohydrate in conjunction with exercise, for the pure purpose of “controlling blood sugar levels” could be a mostly unnecessary endeavor anyways.

8. Low carbohydrate diets, if implemented improperly, result in low fiber intake from a sharp reduction in plant-based food consumption, which can increase risk of digestive cancers and cardiovascular disease, and also leads to constipation and bowel issues. In addition, a drop in fruit, vegetables, legume and grain consumption can result in inadequate phytonutrient, antioxidant, vitamin C and potassium intake. Many (but not all) low carbohydrate diets have these problems.

9. Typical “low carbohydrate” meal replacement bars and shakes, ice creams or ice cream sandwiches, and other low carb or sugar-free snacks often contain potentially unhealthy ingredients like maltitol, and are chock full of preservatives and highly processed ingredients. If your low carbohydrate diet involves boxed, wrapped and packaged food, it probably falls into this category.

10. There can be long term health issues as your body is chronically carbohydrate depleted over extended periods of time. Your liver is exposed to extra stress as it is forced to assist with manufacturing glucose from fats and proteins, potentially toxic amounts of ammonia are produced as proteins are converted into glucose, your body has a more difficult time producing mucus and the immune system becomes impaired as risk of pathogenic infection increases, and your body loses the ability to produce compounds called glycoproteins, which are vital to cellular functions.

So is it possible to “do a low carbohydrate diet right”?


And later this week, I'll be posting more about low carbohydrate diets, potential benefits, and how to do a low carbohydrate the right way.

But until then, feel free to leave your questions, comments and feedback below.

133 thoughts on “The Hidden Dangers Of A Low Carbohydrate Diet

  1. Hi, I notice that this article and some comments have mentioned that the liver manufactures glucose from fats. Isn’t this totally untrue? I thought it manufactured ketones from fats and those were converted into ATP? I know protein is converted to glucose but I thought fats converted to ketones, not glucose, and ATP is made from the ketones and not glucose at all.

  2. I have been doing the keto diet for about 3 weeks now and I feel great. I also take magnesium and potassium supplements daily to make sure my electrolytes are okay..

    I just watched a video on YouTube of a young girl doing keto for one month and she passed out. Her doctor said it was because depleted all of her glycogen stores and that her brain and heart were not functioning properly because of this.. She said the doctor told her this is unsafe and could cause a heart attack, and that a heart attack at such a young age wold mean death, so she should stop the diet, or do it underr professional care.

    Is this true? I would also like to know if there is anything I can do to prevent this?

    1. Hi, it sounds like your friend may be one of those that cannot adequately function on a ketogenic diet, there are some such as diabetics that will die if they go on a keto diet! That being said, just look up ketogenic diet therapies for Epilepsy. It’s the most mainstream use of a ketogenic diet in a clinical setting. It’s a prescribed therapy that sometimes is the only solution for tough cases of Epilepsy. Furthermore, it’s almost ALL children that are prescribed this diet. And this is in major hospitals and legitimate health practitioners. It’s not junk science or hype. So if your friend was on the verge of a heart attack, they may well be one of the few who cannot support a keto diet. And this is indeed very dangerous and fatal to those who’s body’s cannot support keto. I know some diabetics fall into that category but not sure what others. Hope this helps. For clinical settings/hospitals, it’s stated that the person on the diet should always be monitored by a doctor. But many including myself do keto without clinical monitoring. I haven’t had issues.

      1. Hi I just saw it was a video you saw, not a friend lol. Anyway, if you’ve been okay for 3 weeks, it seems impossible to me that you are one of the rare cases that cannot do keto. I’m not a doctor but it seems like it’s totally fine for you. You’d know if you were in acidosis by now, you would have died already. lol.

  3. Hi Ben,

    I was very interested in your comment about mucus production. Throat cancer treatment from 3 years ago left me with impaired salivary function. I went on a keto diet about a month ago, and about a week later got a sore throat that wouldn’t go away. A strep test came back negative, and i have no other viral symptoms. Could this be simply irritation from dryness? Can you point me to more information about how mucus production becomes difficult in ketosis?

  4. I cannot see anything wrong with eating meat, fish, chicken and vegetables. This is good clean eating… and naturally weight loss will occur. I have lost 25kg on a keto diet and there were not any wrinkles on my face because of the natural fats, i.e. butter, cream etc. I cannot agree with you… it is not a all or nothing approach as they state you have to introduce carbs after two weeks…

  5. Dear Ben,

    Like your article. I have been working the keto diet since February. At first just low carb and pretty much no fiber. I had irratic stools for about 6 weeks. Now normal. I did realize I need the big 3 in my diet and alot from vegies. I do eat a lot of vegies like asparagus ,zucchini, cauliflower pretty much all above ground vegies. I cheat and make roasted turnips as a sub for potatoes really works satiate that craving.

    So, I do work out with weights. Interestingly have been picking up weight amount by about 30 lbs over diet period. I lost initial 10 pounds, but no more. I have lost inches all over. Look better , feel better.

    My new go to food is hemp hearts!!!

  6. I had to stop low-carb because of marked gastrointestinal side effects. Within days of added carb/fibre from grain (whole grain primarily) and cut back meat and fat, my system began to normalize. I have gained most of the weight which was, of course, water. And that lack of water in my system was creating terrible illness in me. I am now eating about 100-150 grams carbs a day, which includes two (2) small bran muffins (which I prefer to cereal), pasta or rice a couple times a week, and cutting out bacon (loaded with nitrates anyway and so expensive) and cruciferous which I seem unable to digest without heightening IBS symptoms.

    I really don’t think I can go back on low carb. I have diverticulitis and impacted gall bladder, so it’s complex. I refuse to use laxatives, which I did have to for a couple times. That’s not healthy. I also learned eating breakfast (with fibre and carbs) was essential to regular and predictable peristalsis, which is also healthy. I really didn’t like doing that either, because I don’t like to eat breakfast. I’ve worked that out by eating very early morning. By 10 or so I can exercise. Do you have any suggestions? I am 75.

    1. …3 litres water a day, while low-carbing, but it made no difference to gastrointestinal distress. I have also added back legumes, in small amounts, and usually with some meat protein.

    2. It sounds to me like you may have a small intestine bacterial overgrowth.
      This is the type of deep dive I usually do a consult for. I'd be happy to help you via a personal one-on-one consult. Just go to…. and then choose a 20 or 60 minute consult, whichever you'd prefer. I can schedule ASAP after you get that.

      Check this out for starters <a href="http:// :” target=”_blank”> <a href="http://:” target=”_blank”>:
      Also there is an entire hidden chapter of my book beyond training devoted to that ;)

      I am not a doctor and this is not to be taken, interpreted or construed as medical advice. Please talk with a licensed medical professional about this. These are just my own personal thoughts and not a prescription or a diagnosis or any form of health care whatsoever.

    3. I just found out this week that I have some Diverticulitis, fatty liver, pre-dibetic, cysts, my gallbladder is thicking and the stuff hooked to it, and I am really consipated… I am also overweight, 46 years old.. I need to find a diet plan that will work for me. Keto was subjested.. but reading this and other side effects.. Could this help me if I added power fiber to some drinks?? With diverticulitis I have read that high fiber diet is important but adding more fiber via grains products also raises your sugar intake.. Any subjestions? Oh my fatty liver is not from alchol, it’s from high carb diet..

  7. I started a strict low carb diet in January and have lost 40 pounds in 3 months. I see a difference but not a 40 pound difference. It makes sense now that it may be a significant amount of water weight I’ve lost. Thank uou. I was curious if you could tell me if I am depriving myself long term. My diet is simple, I only eat fish, green vegetables, berries, pecans, cheese, and milk. I snack on pork rinds and beef jerky occasionally and have coffee and tea a couple times week. I am diabetic and this diet has helped tremendously. I also have had liver problems in the past and don’t want to damage it anymore if I may be doing that. Thanks for this article and your response. Sincerely.

  8. I am counting calories and have lost an average of 2-3 pounds a week for the last month. My boyfriend started the Atkins diet (just meat, eggs and cheese) he eats no veggies at all, and dropped 8 pounds in one week. Very discouraging for me since i’m walking 5 miles a day and eating an 800-900 calorie diet daily. He is not exercising and dropping in a week what takes me a month !.. I tried his diet for a couple weeks and still only lost 2 pounds a week and my cholesterol numbers went threw the roof (never had cholesterol problems before) so I stopped it. Why does it seem easier for men to lose weight vs woman. ? My bf has dangerously high blood pressure always for years but when he is on Atkins his blood pressure goes to normal.? I just feel this is not a healthy way for him to lose weight but he loves the fast results. Am I wrong do not want to encouraging to continue his diet long term ?

    1. Hey Jackie, everyone responds to diets differently. I would start by reading through these:… and this:… and then if you want to go into detail feel free to book a consult at <a href="” target=”_blank”> and choose 20 or 60 minutes and we'll get you scheduled to go into detail in a Skype consult. Hope that helps!

    2. I just started a low carb diet today as I’m finding low cal too hard right now. I am a 65 year old female and work out at least 4 day a week including weight training. I’m fit but need to lose 20 lbs. I’ve read that you should have no more than 20 or 30 g of net carbs per day, depending on the website. Today I am doing yogurt, strawberries, egg, ground steak, salad, chicken, other veggies and some cheddar. Net carbs 21. Looked at the calories as well and they are just over 1200. How many net carbs should I be getting since I workout?

  9. I run a Modified Ketogenic Diet and have no problem performing sprint intervals or heavy weight training. It’s a matter of adapting your body under whatever nutritional protocol you’re working with.

    1. What exactly is a “modified” ketogenic diet? To me that would be like saying I’m partially pregnant.

      1. I have been running 10 miles daily and do 1 hour of weight training on Keto. My body fat is now stable at about 7% and my weight is also stable at 72.5 kg down from 80 Kg and 16% body fat (relatively muscular body). The bulk of the fat loss was on Keto and the first easier part of the loss was on low carb.

        As for running, I eat a medium banana in 5 equal portions during my run and drink 12oz low carb electrolyte . I also take a Gu but split it in to 4 portions. I do feel that my muscles are a little less bulky which I don’t mind but my strength is either the same or slightly higher.

        I eat more greens than ever before. I no longer take or need my constipation supplements. The nutritional information I gained in preparation and while on Keto are perhaps the most valuable of my Keto experiment.

        Many live on Keto, I personally do not believe it is normal to stay on Keto indefinitely. Maybe 4-6 weeks at a time is fine if you are a healthy person.

        I am almost hooked now on Keto. Once in, I do not want to get out. I will soon get out though but only after I test the boundaries of eating carbs and proteins before, while and after training.

        My only problem now is to remember to eat :)

  10. I’m 24 and worried that I could have done long term damage to my body. I was very low in carbs for 2-3 years and have slowly started adding some more in. Right now I’m at 80 a day and plan to add in more. Is there anything I can do to get my body back on track from being depleted from carbs for that long? I noticed an increase in energy when going from 20-40 a day. Will I continue to feel better going towards 100 or 200?

  11. Please comment on the right way to do a low carb diet. How many grams assoc with what activity level.
    Thank you

  12. The point you made about glycogen stores is important, acrbs are required for all body functions like powering the cells, signalling and everything which happens in the body.

    So i don’t believe in Low carb diet , low fat diet or a low protein diet, we need to balance our diet in a fashion to receive all required cellular nutrition.

    After a thorough working I could understand there are four major causes for type 2 diabetes

  13. In a much earlier reply to comment, you stated that low carb/high protein is a mistake, especially for women. Can you please elaborate on this? I think this is a mistake I may be making.

  14. I disagree with 4., 5., and 6., and forgive me for not reading “How to do low carb right.” I’m fat adapted, and doubled-down about 3 weeks ago to limit carbs to 50g or less per day while increasing fat. I’ve lost 5 pounds too without feeling hungry- I haven’t seen 143 pounds on the scale in a decade and have recently. I eat a wide variety of colorful fruits and vegetables. I’m not dehydrated. I ran a 4×400 interval workout yesterday in typical lap time (1:27 in 80 degree heat in direct sun) which is the pace I ran for intervals on 100g-200g/day of carb (including gels and sweet potato refeeds) when training to BQ last fall on much cooler days. I did a Murph on Memorial Day with the 20 lb. vest in 49:34, which is at least as good as other CrossFitters my age (I’m not a regular CrossFit guy). A Murph isn’t so much about intensity as it is pace, assuming one is conditioned. I continue to lift heavy and haven’t lost any performance in the gym and my weekly 30 miles of running is not impacted by low carb. In my n=1 experiment I can claim that my athletic performance hasn’t suffered nor has my health.

  15. Hi Ben,

    question with regards to glycogen stores in muscles. Say you use all glycogen you have during your workout. How long does it take for our body to replace it? Does body have a mechanism to replace that glycogen from fat stores or does it come only from food intake (e.g. starches etc.). Can you recommend any reading on this topic?

    Thanks a lot!


  16. Glucose from fat ? What a nonsense, body start tu uses ketones when carb are off for a certain period of time and of course you eat enough fat.

  17. Ben, now that I have come across your site, I have hope. I started Atkins 2 months ago. I feel horrible although I have lost 40 pounds. I thought in time, my body would regenerate and feel better. A flight of stairs makes me have to sit and catch my breath. I copied your recipe for the smoothly. I am 59, out of shape, have liver disease and some disability but this will not stop me from succeeding. Is it possible to get a meal plan. May be just a couple days work. I will be traveling soon and need to get 50 more pounds off and feel some energy. Yes I am smaller now, but I feel like crap. THANKYOU in advance for whatever you van share with me via email-

  18. Hello Ben,

    I am 52, Asian, 168cm/ 80kg on Keto diet. I do combination of weight training (2x a week) and HIIT sprints on weekends. My goal is to increase growth hormone.

    Am I doing it right considering my goal? or is there better way to increase growth hormone? Thx.

    1. This would be a great question to call into the podcast: natural ways to increase growth hormone. Here's how you can call this into the podcast: go to and try and keep it under 1 min!

  19. I was looking at the superhuman food pyramid and it just states # of servings per day but im confused as to how much you deem a serving of the recommended foods. Where can i find those amounts. Thank you

  20. I’m have insulin issues and need to be on a low glycemic (which is low carb) diet. This article worries me that I’m doing it wrong. I don’t really eat much fruit because it its sugar content. I eat eggs and a whole grain English for breakfast, a Greek yogurt for snack, usually an all protein lunch or a salad and for dinner protein, green veg and a tiny bit of a brown carb or just a big salad. I’m I doing okay??

  21. Ben:

    The assertion that “a high fat or high protein diet produces just as much insulin as a high carbohydrate.” is not supported in any of the research you provided above.

    The only study offered above – and its a stretch- that comes close to supporting your claim is the last article. However, it really doesn’t support your claim. This study doesn’t really tell us much of anything other than whey protein in this study had a pro-insulinogenic effect that is greater than white bread in this study. The study should be considered an outlier and can;t be used to extrapolate more that what is stated. Most people are not choosing whey protein over white bread and diets effect on body chemistry is more complicated than this very simplistic study. Note –high protein can cause higher insulin in the absence of carbs due to glucogenesis. Yet this does not happen with fat.

    If you were to compare a Ketogenic “diet” to a traditional american high carb “diet” you would find very different results to your claim. In that the Keto Diet would produce a much lower amount of insulin that the high carb diet.

    Further Non of the studies you offered say anything about fat producing as much insulin as a high carbohydrate diet. Which fat does not.

    I would encourage you to discuss your claim with Drs, Peter Attia, Dom D’Agostino, Jeff Volek, or Steve Phinney and would be very interested in seeing their response.

    Thanks for reading.

      1. However, the effects of fat intake on insulin action and glucose metabolism in humans are less clear

        Thats what the bottom article said. We are not “lab rats”. Bad study or comparison.

  22. Can you be more specific as to the studies or research that supports your claim ?

    When navigating to the link you provided”” the main page

    message I get is “Sorry, the page you were looking for in this blog does not exist.”

    Maybe you seeing a cached page.

    Also, I’m looking for real research studies. There information I provided is based on real, current & reproducible scientific studies.

    1. Akhavan T, Luhovyy BL, Anderson GH. Effect of drinking compared with eating sugars or whey protein on short-term appetite and food intake. Int J Obes (Lond). 2011 Apr;35(4):562-9. Epub 2010 Aug 24.
      Baggio LL, Drucker DJ. Biology of incretins: GLP-1 and GIP. Gastroenterology. 2007 May;132(6):2131-57.
      Claessens M, Calame W, Siemensma AD, van Baak MA, Saris WH. The effect of different protein hydrolysate/carbohydrate mixtures on postprandial glucagon and insulin responses in healthy subjects. Eur J Clin Nutr. 2009 Jan;63(1):48-56. Epub 2007 Sep 12
      Gerspach AC, Steinert RE, Schönenberger L, Graber-Maier A, Beglinger C. The role of the gut sweet taste receptor in regulating GLP-1, PYY, and CCK release in humans. Am J Physiol Endocrinol Metab. 2011 Aug;301(2):E317-25.
      Lavigne C, Tremblay F, Asselin G, Jacques H, Marette A. 2001. Prevention of skeletal muscle insulin resistance by dietary cod protein in high fat-fed rats. Am. J. Physiol. Endocrinol. Metab. 281:E62–71
      Morifuji M, Ishizaka M, Baba S, Fukuda K, Matsumoto H, Koga J, Kanegae M, Higuchi M. Comparison of different sources and degrees of hydrolysis of dietary protein: effect on plasma amino acids, dipeptides, and insulin responses in human subjects. J Agric Food Chem. 2010 Aug 11;58(15):8788-97.
      Ranganath LR, Beety JM, Morgan LM, Wright JW, Howland R, Marks V. Attenuated GLP-1 secretion in obesity: cause or consequence? Gut. 1996 Jun;38(6):916-9.
      Salehi A, Gunnerud U, Muhammed SJ, Ostman E, Holst JJ, Björck I, Rorsman P. The insulinogenic effect of whey protein is partially mediated by a direct effect of amino acids and GIP on beta-cells. Nutr Metab (Lond). 2012 May 30;9(1):48.

  23. Ben:

    on August 15, 2011 at 9:00 am at… you stated above that “…, a high fat or high protein diet produces just as much insulin as a high carbohydrate. I encourage you to do your research on that matter.”

    Can you provide the research studies that support your claim?

    The reason I ask is that your statement seems to run counter to the state of the art research on high fat, moderate protein , low carb diet.

    The researchers here are Drs. Peter Attia, Dom D’Agostino & Andreas Eenfeldt all seem to refute your statement.

    Please see the links below.……

    Do you still support your claim?

    Please comment.


      1. Also …. Drs. Jeff Volek, PhD. and Steve Phinney, M.D also refute your assertion.

        High-carb diet = high insulin levels = burn less fat and store more = get fatter and fatter

        And then, as a corollary:

        Low-carb diet = low insulin levels = burn more fat and store less = stay lean

        One note –high protein can cause higher insulin in the absence of carbs due to glucogenesis. This does not happen with fat.

  24. Also im 45 yrs old and have a young family which is why im adking for help my test injections ate only to help yhe muscle around my spine and I take diasapan and tramoset for pain relief, its hatd on my back but I do work hard and need to lose weight as fast as possible before an op next year, like I say any help would be greatfull..

  25. Hi Ben, I may be a pain but im stuck and need help, I thought I was on a carb free diet for s month and after reading all this I may have not, iv had chicken, fish n veg but know bread tatts or rice n pasta, am I ok as I weighing 16/9 st and im in the gym every and have six bust discs, its hard training but I push through with painkillers and s course of testosterone, im fighting the fat back but some help losing the weight and still gaining muscle would help me alot, please guide me on email if possible mate and thank you for reading this, regards kenny ward

  26. Hi Ben,

    I am type 1 diabetic of 46 years and a personal trainer. I’m quite active, however wish to bring my fat % down to approx 16. I am 5’6″, 130 lbs., BF 18.2, A1C of 5.1, with fat around obliques. My dailey intake of carbs is 20-25 g because it helps keep my sugars more stable. My nutritionists says I may not be able to lose the fat around my middle due to my insulin intake. I am also trying to find a shred diet for someone like myself. I burn approx. 4000 cals per week due to my consistent workouts. I love your confirmation regarding low carbs but currently at a standstill for myself.

    Can you suggest a nutrition plan for someone with my goals. Thanks,

  27. Thank you so much for the information.

    I play Softball, at least 4 days a week and often every weekend all day.

    I recently went on a low carb to lose weight but also to sort of get my body back to basics. I lost 10 lbs in 2 weeks. Great news Except I have for the first time ever sustained 2 leg injuries, same leg. 1 pulled muscle in the groin, and the other (happen last night whilst running to 3rd base) I pulled a hamstring.

    I have been playing for about 7 years and never had a problem, know how to warm up etc.. I didnt think its a coincidence that this happened at a very similar time.

  28. hello. i really need your help in this. I have been on a protein diet now for 3 months..eating exactly everyday: oatmeal(1 egg, 2 tbl spoons oats, and 2 table spoons zero fat yogurt) with cheese and thyme and 1 tbl spoon olive oil and coffee with zero fat creamer for breakfast… grilled chicken breast for lunch… and 2 grilled eggs for dinner..some times i add another cup of coffee with creamer or cadbury highlight…. i have lost 6 killos… which is a lot for me as i am only 54kg now so i wasn't fat just chubby…i still have 2 to 4 killos i wanna lose but i am kind of facing plateau… i m an athletic person doing cardio training… yesterday i started doing weight lifting and will be stopping cardio for a month ( a program i got from… i wanna build muscles and burn the last few kilos of fat..but i am afraid of my diet as i dont take carbs… will i be able to do so by staying on this diet? i want to note that first my metabolism is a mess as i spent my life dieting…and if i should eat carbs now how should i do that..since as u know after a long protein diet any little amount of carbs will be stored easily… and i really cant gain back weight…i did a very hard job losing those kilos…plz hekp me..thank you

  29. Thank you for the low carb. Article. I have a neighbor friend that has been on the Atkins diet for over 15 years. He used to cook sausage 3xweek and I talked him into the 1xwk or less because of the high content of fat. He is now diagnosed with severe depression. Didn’t know if their might be a correlation.

  30. Hi, Ben. I’ve been on an extremely low-carb diet for two weeks, eating 1000-1200 calories per day. I lost 10 pounds in the first week, and am now 138 pounds. I’m a 6ft tall, 18-year-old male. For months I had been compulsively overeating sugary foods, going from 98 pounds to 155 pounds in just a few months. Now I’ve quit cold turkey, but realize from your article that this type of deprivation can be injurious to my health. Have I done too much damage already in 2 weeks, or does my metabolism have yet to significantly slow down?

  31. Low carb high fat diet have one more problem. I think this is the big problem. I had before couple of months of a strickt LCHF diet for about 3 years. I do hidrocolontherapies once a year. My therapist says that people that eat too much meat and protein as all have big chances to stick foot in the gut or colon. We need to eat potatoes/starches/ only for one reason , our body cant digest starch and the main purpuse of the gut is to remove these starches from the body. And the starch is used as transport for the other food that is in the gut. Also other foods are not digested and used for transport – cellulose, onions and others.
    Ben, i think will be good if you make one podcast with theme hydrocolon therapies. This is the first step for everyone that want to be healty and want to live longer. With these therapies the body is cleaning at cellular level! And after that the body digest and absorb better and more micro and macronutrients at all.

  32. After being a total butt towards my family for the past week and sick. I realized it was this low carb diet that did it. I would never recommend the keto/atkins diet to anyone ever again . I would rather be healthy happy than thin and unhealthy.

  33. Hi–I'm 2 weeks into a ketogenic diet prescribed by my doctor (traditional western medicine, believe it or not!) in an attempt to help my lipid profile, without increasing my statin dose. I have a familial dyslipidemia problem and the women in my family die before 60 of sudden cardiac death, so. . . I'm willing to do this. I've always eaten quite low carb (~100g/day) but all this fat is very new to me.

    I'm doing tons of research trying to weigh risks and benefits of this approach. Once I'm sure I've keto-adapted (i started spilling ketones pretty quickly after starting –I think b/c I've been low carb so long and workout hard), I think I'll try doing some kind of carb cycling–for my workouts (Crossfit–which sucks bad right now), if nothing else.

    But right now, my question is about the information about long-term ketosis being dangerous for our immune systems. You write:
    "our liver is exposed to extra stress as it is forced to assist with manufacturing glucose from fats and proteins, potentially toxic amounts of ammonia are produced as proteins are converted into glucose, your body has a more difficult time producing mucus and the immune system becomes impaired as risk of pathogenic infection increases, and your body loses the ability to produce compounds called glycoproteins, which are vital to cellular functions."

    I haven't been able to find an research on this–can you provide some links to the studies that explain this and document the evidence for it?

    Thanks in advance!

      1. Do you have actual scientific research? .com and blog sites are not scholarly sources. I’m not trying to be rude. I just truly want to read the research. Thanks!

          1. I think the issue was concerning the claim that keto causes liver damage – or to be more precise: “our liver is exposed to extra stress as it is forced to assist with manufacturing glucose from fats and proteins…”

            Any scientific evidence to back up this claim?

            And I’m not trying to be rude, either :-)

  34. Ben my girlfriend has just dumped me and is a no carb diet. She has become emotional for no reason at all. Does this have anything to do with the diet?

    1. Hard to say. The "carb flu" can make people emotional if they aren't compensating correctly. Especially if she was VERY addicted to carbs and went cold turkey. Or maybe you are looking for a scapegoat? Jus sayin'…

  35. My husband and I are starting a diet which is only going to involve lean protien (chicken, turkey mostly) and only getting carbs from vegetables that we will blend in our ninja blender. I know we must stay hydrated but I was told to only drink distilled water with electrolytes such as Smart water. Is distilled water best?

  36. Hello. I am a 34 year old female and suffering from the effects of a low-carb diet. My naturopathic doctor put me on the Paleo diet due to me being insulin resistant. After four plus months of following this diet, I weigh 100 pounds and am dealing with anxiety attacks, depression, low immunity (just trying to get over the cold/flu), no energy (no exercise), etc. I am now eating carbs such as rice bread, baked potatoes, millet, oatmeal and of course fruits and vegetables. Any further advice on how I can reverse the effects of this terrible diet? Thank you.

  37. I spoke with a doctor last December 2011, cosmetic surgeon, and she suggested 30g of carbs per day for women over 55 years old like me trying to lose weight with no success. I resent her suggesting that since I've been reading that could've caused serious complications and bad side effects like kidney stones. What are your views and can any damage from being on this regimented diet be reversed? I eat more carbs than that now but was restricting carb intake, from fruits mainly and whole grains, for several months.

    Thanks for the feedback!

    1. The kidney stones would only be an issue if you replaced that carb intake with PROTEIN rather than fats…you simply need to ensure that you are eating a high fat, moderate protein, low carb, and not traditional "Atkins style" high protein.

  38. I long should it take to remedy the "see-through" skin problem. I am 40 years old. I have now started eating plenty of good carbohydrates and drinking lots of water. (I have to admit that I was not drinking much water at all earlier so I think my skin got severely dehydrated) Can I get my skin back and hide my veins again?

  39. I have a question. I did a low carb diet for about 3 months and I lost 4 kilos. I work out a lot, running and weight lifting. After about 3 months all my veins started showing really bad. It looks awful and I hate it. (I am a female) It is like my skin has turned into glas, all veins show. I also feel that my muscles are less toned. Why is this? How can I fix it and get my body back ? Please help – I am desperate!!

  40. You are wrong on some very key points here Ben. Carbs are not required by the body to survive, and you are not going to "run out of glycogen" as your body will make more. What you are saying might be true for elite athletes, but for the "average joe", even an active one, it's simply false.

    There are plenty of elite athletes who do not eat carbs and who survive just fine, including Triathelete Jonas Colting.

    The fact is if you are eating a high fat, moderate protein, low carb diet your body will run just fine, even doing training that you have suggested would be impossible.

    1. Mathew, I'm afraid YOU are wrong. The body does need glucose for several small organ functions (although not as much as common nutrition advice would lead us to believe). Re-read my article. I didn't say you need much glucose, but you do need trace amounts from dietary sources.

      1. Thats what gluconeogenesis is for. What on no carb high fat low protein your body converts proteins and fats into a very small amount of glucose for your brain. This is called gluconeogenesis and it is done so without eating any carbs so ben you are wrong

  41. Looking forward to your article on Friday. I am 13 weeks out from IMAZ (are you doing that race btw?) and would like to drop 10-15 lbs before then. I did the TIm Ferriss slow carb diet from Oct to Feb of last year and lost 30 lbs and dropped 25 minutes off my half marathon time. Is that diet good for IM training? I did a lot of beans, mixed nuts, chicken, eggs, etc.

  42. Thanks for this Ben! I am a relatively new female triathlete who is 5'5" 117, pretty lean to begin with. I just started Paleo this week and lost 3 pounds in 3 days. I like the diet, but am concerned that I may lose too much. Any ideas you might have for the lean endurance athlete eating paleo? What types of high-fat foods might make more sense to be sure to include daily? Thanks again!

    1. Most of what you lost is glycogen/water weight. That's pretty typical! Don't worry – that rate of weight loss will subside after 5-10 days. I'll be posting more on this Friday about high fat foods, etc.

  43. Great article, Ben. I trained for an NPC Bikini competition last year following traditional wisdom, you know, oatmeal, lots of protein shakes filled with chemicals, depleting water, etc and got down to 112 lbs at 5'3" and felt like death. Afterward, I went carb crazy and gained back 5 pounds by New Years. Back in the spring, I was reading a lot about low-carb Paleo and started doing that. I didn't lose an ounce. If fact, I got up to 130 lbs, all the while doing HIIT and weight training 5 days per week. After a couple months, I started eating more plant foods and cutting back on the protein and fat. I feel much better now, but I can't lose any weight. I've been at 134 lbs for over two months now and my digestive tract is not what it used to be either. (I'm taking digestive enzymes for that.) I feel like my body just went haywire on low-carb. Is it possible that some people just are not meant to "run on fat" like the Paleo crowd preaches?

  44. From your comment #4, you seem to insinuate that your body prefers to burn carbs for fuel and will do so as a priority until the carbs are depleted, after which it will resort to burning fat for fuel. I came across a similar insinuation during a lecture in my Human Biology class the other night as well. This confuses me. I had thought if you're in an aerobic state your body would burn fat for fuel and not resort to burning carbs until you're in an anaerobic state. If carb stores are full, lipid stores are full and protein stores are full what fuel source does your body choose when in resting up to aerobic state.

    1. Our bodies are usually burning both glucose and fatty acids SIMULTANEOUSLY, however, glucose left free in the bloodstream is toxic (which is why insulin-dependant diabetics go blind, lose a foot or require dialisis), so the body prioritizes using available glucose first, shutting down fat burning in the meantime.

  45. Looking forward to your podcast, I did Atkins and it worked for me loosing weight, the second wind of energy comes I think after week of being on it, and you are spot on with having limited energy reserves I did notice this. I mixed up my meat with lots of veg and did my best to stay hidrated, the whole thing seemed right but wrong at the same time and something aimed more up the middle and balanced is probably the answer to this kind of fueling for the body.

  46. Interesting opinion, but that's all it is, and it's full of problems. You say low carbers suffer from high amonia byproducts because they produce too much glucose, yet they suffer debilitating effects from not getting enough glucose. Both sides are rubbish and abviously both can't be true. Produce one case of too much amonia please. Our bodies need very little glucose, and burning fat is not that slow. It does become slow when you overload yourself with insulin, but that;s why HFLCers do what they do. They become fat burning engines. Many athletes are now converting, and nobody is shrivelling away. Grok on! The hardest argument to take is your disease card. There's absolutely no proof that fiber does anything but make you poop more often and smell more. There's no proof that fat causes heart disease. There's no proof that fiber reduces cancer risks. Nothing! On top of that, you'll find that most low carbers eat much more plant fiber than the average person. It's not all bacon.

    1. Afraid you have it wrong, John. I never said ammonia byproducts were from producing *too much glucose*, but rather breaking down *too much protein*. I also acknowledged in beginning of article that you only need 600 cal of glucose per day, whether from glycogen sources or diet.

      Next, a high fat or high protein diet produces just as much insulin as a high carbohydrate. I encourage you to do your research on that matter.

      Finally, if you go read or listen to anything I've written on fat, I have already pointed out that fat does not cause heart disease. And there are literally hundreds of research studies that demonstrate chronic disease reducing benefits of fiber.

      Like I said (and you would realize if you had actually read my article carefully, instead of skimming and jumping to the comments) – there is a way to do a low carb diet right. But lots of people don't do it right, especially athletes.

      1. >>Next, a high fat or high protein diet produces just as much insulin as a high carbohydrate. I encourage you to do your research on that matter.

        A high fat diet results in just as much insulin as a high carbohydrate diet. Are you sure about that, it's counter to everything else I've read regarding low carb diets?

          1. That article says ZERO about fat produces insulin. Also the studied participants were on a mostly carbs, somewhat fat and low protein diet. Not keto. The body produces it's own glucose only through carbs and protein not fat and insulin can be spiked with protein and carbs because of this. Fat and carbs are pretty much the only things the body uses. Carbs cause issues as humans aren't built for the intake we get with the level of average activity of a human being.

            The only real dangers with keto is if you already have or family has a history of heart and/or liver problems definitely consult with doctor first or just lower carb intake, but don't do keto if you want to lose weight. And most importantly DRINK LOTS OF WATER. You need to flush out excess ketones to avoid ketoacidosis. Which is a type of insulin resistance such as diabetes II presents.

    2. Top answers John. So much error in some peoples understanding of low cabs… or should I say Crap Carbs ? As not one of the Low Carb guys including Atkins say to you need to be Carb free, just mainly crap processed carb fee, and things like High Fructose Corn Syrup. I have been a Low Carber now for 12 years, and at 61, 6 feet tall, I weigh in at 175 lbs and have a 35" waist. I have no illnesses at all and my blood pressure is just 110/70.
      So keep up the good work of standing on what you believe to be a good diet of natural food that does nto kill or maim you.

    3. Many people who are on low carb diet experience constipation,incluidng me,7 days constipated and I was not eating THAT low in carbs,around 80 grams of carbs daily.
      It is impossible to eat more plant fiber than the average person when you are on low carb,I know I am using something that counts all my carbs and etc.Even though I will still eat less carbs than the average person,I will not go very low in carbs because it seems that many people including me had very bad experiences.Moderation is the key.

      1. Mistgoddess, my mag needs go up dramatically when I have more dairy (which I do on low-carb to boost calories), when I’m exercising more (which I do on low-carb since I feel so much better), when I’m either getting more sun or supplementing with vit D, and during the week before menstruation.

        First sign of low magnesium: constipation. Sign it’s way to low for me is an itchy crampy feeling in my right thigh. Usually I catch the first sign and add extra magnesium for a couple days, either orally or via magnesium “oil” used topically.

        Hope this helps.

      2. I’ve found using curry sauce (I can find it in the ethnic section of my supermarket pre-made) with something like ground beef or chicken (I like to make curry based low-carb burritos with MIssion low-carb tortillas) completely eliminated my constipation problems with a low carb diet. I was completely normal and the variety of curry sauce flavors is interesting. Before I tried curry sauce, I found that constipation made the diet unbearable and no amount of fiber supplement helped one bit. But curry is a natural laxative and the difference was amazing.

      3. Fun fact: undigestible fibre can actually cause constipation. Most constipation is from poor digestion related to gut flora and enzymes. Also, LCHF diets simply do not need to be low in fibre.

          1. The body doesn’t process fiber for energy, so “total carbs – fiber carbs = net carbs”. .so a good HFLC Keto diet has plenty of veggies & fiber! This article is highly suspect, but may apply more to an Atkins (high protein, low fat) type of diet.

          2. Sorry, replying to my own comment already. He does mention at the beginning that he’s referring to Atkins-type diets. .I skimmed over that part and dialed into the lack of explanation on high fat versions like keto. .which he was apparently saving for his follow-up article about how to do low carb diets the right way.

    4. I have to second John on the veggie consumption point. Most low carbers absolutely eat more veggies than the average person. Having been back and forth between low and high carbing for many years, I can tell you that without a doubt I eat at least 2 or 3 times the vegetables on low carb that I do when I’m not low carbing. I know this is just an n=1 experiment, but I wouldn’t be surprised if this is a common tendency among low carbers. It honestly makes me wonder how well informed Ben is on what low carbers actually eat. Most of us longer term low carbers that are not just “dropping 10 lbs to look good for that big occasion” are well aware that we cannot live on pork rinds, low carb protein bars and shakes. To me its just common sense that man can and has thrived on a very low carb diet and that if there are any “side effects” or dangers involved, they are not an indication of the dangers of ketosis or a diet low in carbohyrdate, but rather an indication of how far our bodies have come from a state that was very natural for us and how much we’ve screwed them up through bad nutrition.

  47. great topic. looking forward to the article and would love a podcast on what YOU think on the matter. my attempt at low carb is very high in vegetables, which hopefully limits the carb depletion you have talked about. excited to hear what you have to say! keep up the great work

  48. Very interesting, and a topic I would love to hear more about (especially in the context of losing fat while maintaining muscle and improving strength)

  49. I understand that people who are into triathlons and marathons may need more carbs, but what about people who have brief moments of intense training like cross-fitters?

    The main focus for them is high insensitivity weight training and many of them are on ketogenic diets.
    Isn't then this type of diet more beneficial for people who are skinny-fat and want only to get leaner and more muscular and do not care about competing in endurance sports?

    1. Yes, but muscle glycogen is required for Crossfit intensity, unless you want to be a "back of the packer". You gotta be burning carbs to do well at Crossfit, at least acutely (during your WOD).

      1. Wrong. In fact “burning carbs” isn’t even a thing that can happen. Your body can produce all the glucose (and thus glycogen) that you need from Fats and Protein.

        1. Hi Steve, you may be forgetting that the fastest and thereby most efficient pathway for your body to produce energy is through the production of ATP and the production of ATP is linked to the oxidation of glucose in the mitochondria. Burning Carbs as it is referred to by non biologists is far more efficient for an athlete than burning fats or proteins. Yes, if your goal is weight loss than you are correct in saying that your body can produce all the glycogen it needs from protein and fats. However, if your goal is to train intensely and get stronger then a balanced diet including Carbs for training energy and proteins for recovery is the way to go. I cant imagine any tour de France riders or power lifters in training (not cutting down before a show) having a no carb diet. Checkout or search the citric acid pathway and the processes of the ATP production in the mitochondria before making sweeping statements about what is “wrong”.

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