Dangers of Zero-Carb Diets, I: Can There Be a Carbohydrate Deficiency?

It’s frequently said in the Paleo blogosphere that carbs are unnecessary. Here’s an example from Don Matesz, an outstanding blogger who eats a diet extremely close to ours:

Protein is essential, carbs are not…. You can only cut protein so much, but you can cut carbs dramatically.

Dr. Michael Eades has mocked the idea of a carbohydrate deficiency disease:

Are there carbohydrate deficiency diseases, Mr. Harper, that you know about that the rest of the nutritional world doesn’t?  I’ll clue you in: there aren’t.  But there are both fat and protein deficiency diseases written about in every internal medicine textbook.

Such statements made an impression on me when I first started eating Paleo five years ago. But several years and health problems later, I realized that this view was mistaken.

Why Aren’t Carbohydrate Deficiency Diseases Known?

How do doctors discover the existence of a nutrient deficiency disease?

It’s not as easy as you might think. For example, the existence of essential fatty acid deficiency diseases in humans was in doubt right up into the 1950s, even though omega-6 deficiency disease had been discovered and characterized in rats in the 1920s. [1] The reason is that omega-6 and omega-3 deficiencies can occur only on unnatural diets. It was infants fed fat-free formula in the 1940s and 1950s who ended up proving the existence of omega-6 deficiency disease in humans.

Two difficulties have made it challenging for science to recognize a carbohydrate deficiency syndrome:

  1. Lack of an animal model.
  2. The rarity of zero-carb diets among humans.

Until recently, few people save the Inuit ate very low-carb diets, and the Inuit didn’t leave good medical records. As a result, few or no humans developed recorded carbohydrate deficiency syndromes.

This wouldn’t be a problem if it were possible to induce carbohydrate deficiency in animals. However, it isn’t.

Animals don’t get carbohydrate deficiency diseases because they have small brains, meaning low glucose needs, and big livers, meaning high glucose manufacturing capacity. Animals can generate all the glucose they need from protein or from volatile acids like propionate produced by bacterial fermentation in their digestive tracts.

But, as we note in the book, humans are more fragile. We have small livers and big brains, and so the possibility of glucose deficiency is real.

Here is a comparison of brain, liver, and gut sizes in humans and other primates [2]:

Organ % body weight, humans % body weight, other primates
Brain 2.0 0.7
Liver 2.2 2.5
Gut 1.7 2.9

The brain is the biggest determinant of glucose needs.  While other primates need only about 7% of energy as glucose or ketones, humans need about 20%.

Compared to other primates, humans have a 12% smaller liver. This means we can’t manufacture as much glucose from protein as animals can. Humans also have a 40% smaller gut. This means we can’t manufacture many short-chain fatty acids, which supply ketones or glucogenic substrates, from plant fiber.

So, while animals can meet their tiny glucose needs (5% of calories) in their big livers, humans may not be able to meet our big glucose needs (20-30% of calories) from our small livers.

So any carbohydrate deficiency disease will strike humans only, not animals.

How Should We Look for a Carbohydrate Deficiency Disease?

To find a carbohydrate deficiency syndrome in humans, we should look at populations that eat very low-carb diets, such as:

  • The Inuit on their traditional hunting diet.
  • Epilepsy patients being treated with a ketogenic diet.
  • Optimal Dieters in Poland, who have been following a very low-carb diet for more than 20 years.
  • Very low-carb dieters in other countries, who took up low-carb dieting in the last 10 years as the Paleo movement gathered steam.

We should also have an idea what kind of symptoms we should be looking for. Major glucose-consuming parts of the body are:

  • Brain and nerves.
  • Immune system.
  • Gut.

The body goes to great lengths to assure that the brain and nerves receive sufficient energy, so shortfalls in glucose are most likely to show up in immune and gut function.

So, we’ve mapped our project. Over the coming week, or however long it takes before we get tired, we’ll investigate the evidence for carbohydrate deficiency conditions in humans.

Related Posts

Other posts in this series:

  1. Dangers of Zero-Carb Diets, II: Mucus Deficiency and Gastrointestinal Cancers A Nov 15, 2010.
  2. Danger of Zero-Carb Diets III: Scurvy Nov 20, 2010.
  3. Dangers of Zero-Carb Diets, IV: Kidney Stones Nov 23, 2010.


[1] Holman RT. The slow discovery of the importance of omega 3 essential fatty acids in human health. J Nutr. 1998 Feb;128(2 Suppl):427S-433S. http://pmid.us/9478042

[2] Aiello LC, Wheeler P. The expensive tissue hypothesis: the brain and the digestive system in human and primate evolution. Current Anthropology 1995(Apr); 36(2):199-211.

Leave a comment ?


  1. This is a subject I am very interested in, thank you for covering it. After years of low fat high, carb dieting, I have been low-carbing for about a year, using coconut oil for about 3 years. After learning of my gluten intolerance, I went very low-carb/Paleo, and lost 10 lbs, but I haven’t been able to lose anything more since. I wonder if the very low-carb eating damaged my metabolism even further, or if it will simply take a while for my body to heal from years of gluten poisoning. When I first removed gluten, my GERD and brain fog disappeared. But now, one year later and gluten-free, the GERD has returned, and I had a nasty gastro thing a month ago as well. I hope you can provide some insight about very low carb eating for those of us who want to heal for good. Thank you.

  2. It is hard to get zero carbohydrates, so I doubt we see much evidence of carb deficiency in “normal” people (i.e., people able to absorb carbs). Green veggies have some carbs, and some low carb dieters miss “hidden carbs” in natural foods. But I am interested to see what the research says.

    That being said, the strictest ketogenic diets I’ve read still have 30 to 50g of carbs daily. Is there a connection between the amount of carbs needed and the optimum blood sugar level? I’ve read it only takes about an equivalent of a teaspoon of table sugar to provide the blood glucose level you need. I would be surprised to find carb deficiency in people eating even on the low scale of the most ketogenic diets.

    I have read where type II diabetics, who test blood glucose regularly, have had blood glucose problems when trying to go “zero carb”. They do better with a low level of carbs. As far as I have been able to find, there are no studies supporting these accounts on the forums out there.

  3. I’m so glad you’re writing about this. There’s so little information out there about it and from my personal experience with low-carbing, I get really sick when my carb intake drops below a certain threshold (usually around 60g a day). I’ve met other people who get this too– not just dry eyes/ mouth, but headaches, spaciness, dizziness, depression. Of course I have absolutely no scientific research on the matter :). Adding things like yams back into my diet helped me immensely.

    Thomas Cowan wrote a very interesting article on GAPS diet and how it’s not effective long term. It was in the Wise Traditions Spring 2010. Do you have it? If not I can scan and email it to you.

  4. While it is true that the brain consumes 20% of the body’s energy input, the brain can also transition to using ketones for up to 70% of its energy requirements. This means that ultimately the total glucose requirement for the body is only about 6%. Still not a trivial amount by any means, but it’s a lot less than the 20% alluded to in your post.

    Of course, this doesn’t rule out the possibility of a “carbohydrate deficiency” issue in humans, so I look forward to seeing any evidence you may find in that regard.

  5. Hi suzan,

    Well, see what you think as the series progresses … but I do think there is a danger of certain kinds of gut infection developing on zero-carb diets.

    Hi Frank,

    With 5 liters blood and blood sugar of 90 mg/dl, the average person has 4.5 g glucose circulating. 1 teaspoon of sugar weighs 4 g. But blood sugar is constantly being withdrawn and replenished, about 5-6 g/hour, so the amount of glucose in blood is not a measure of daily needs.

    We recommend 50 g glucose or starch = 200 calories for ketogenic dieters. This is for protection against possible glucose deficiencies. But epileptic diets have often gone below that. I think people are now realizing that it’s not necessary to severely restrict carbs to achieve ketosis, and that diets with some carbs work better.

    Hi rebecca,

    I had a lot of those symptoms myself, and it was connected to my chronic infections. Now I tolerate long fasts much better, but still have to be careful.

  6. Hi Gary,

    Yes … but the body’s glucose requirement is not limited to the brain. We have calculations of glucose requirements in the book, there is some endogenous production of glucose but consumption net utilization [PAJ: edited for clarity] of glucose is probably at least 100 calories per day above the needs of the brain and nerves, and during infections potentially much more.

    That’s why the second mention of glucose needs was 20-30% rather than 20%. In the book we call it 600 calories, higher during infections or in elite athletes.

  7. wow, great post. I just wanted to tell you that i’ve just finished a self-experiment where i ate solely of animal products from July 13, 2010 through October 25th, 2010 (just a couple weeks ago). I can tell you everything i ate, body comp changes etc if you’d like. I was absolutely strict. Im now back to “normal” paleo with maybe 50-150 grams of carbohydrate per day. No starch though, its all from salads with lettuces, broccoli, cauli, tomatos, peppers, etc.

  8. I am looking forward to the series. I upped my carb intake, as per your recommendations, but the only difference I have noticed is that I will occasionally feel bloated after a meal. Its mostly when I have sweet potato or potato, but it doesn’t happen with rice so much.

  9. Very interesting post and looking forward for the other posts.

    I did hear about people developing hypothyroidism after being on very low carb diets for a long time and it got me curious about it, because other aspects of such diet seem pretty positive.

    In your series on healing bowel disease, you also recommend having some starch, but I found that some people with conditions like Chron’s and SIBO react very badly to any carbs, especially starch. I’m dealing with SIBO problems myself and as per your recommendations and after being zero-carb for months I tried a small bowl of white rice, but it was a disaster and the bacterial overgrowth got worse. For me, it’s the same situation with fermentable fiber, inulin and FOS. Everybody seems to be in absolute admiration with those sources of fibers, but people with some forms of bacterial overgrowth are having troubles with them also feeding the unwanted bacteria. I have to carefully make sure that the probiotic I take doesn’t contain any FOS or I’m in for troubles. It’s often a very hard situation to be in because people also often recommend antibacterial agents like coconut oil, olive leaf extract and many others, but I found that those will unfortunately also make life difficult for beneficial bacteria if it lost the balance of power in the gut. In summary, anything that feeds the gut flora makes it worst, but anything that kills it also makes it worst, no matter the amount of beneficial bacteria introduced at the same time.

    What is a SIBO, Chron’s, epileptic or chronic migraine sufferer to do if carbohydrate is effectively found to be needed in some amount? It seems odd to me that a very low carb approach would be so beneficial to some people while also creating a deficiency. It might be a bit like iron being essential to life, but absolutely disastrous to some people with specific conditions.

    Also, it seems to me that the Inuits are far from the only traditional group who’ve been on zero-carb diets for significant amounts of time. It seems to me that many paleolithic groups in many regions of the world throughout history would have had periods where carbs were very rare. In many regions of the world and for most part of the year, sources of carbs like fruits and starchy vegetables are seldom available in nature. Maybe getting out of ketosis one or twice a year is enough to overcome any possible problems seen in long-term zero-carb diets.

    Finally, there probably was other sources of starch available to paleolithic men, but it seems to me that the variety widely available today is very limited. If we put aside rice since it wasn’t available back then, can we assume that the only sources of starch would be potatoes, sweet potatoes and taro? It also seems to me that those sources of starch, if eaten very regularly, can bring about problems. Potatoes are known for their saponin load that could cause problems to some people with prior gut or autoimmune problems and sweet potatoes and taro seem to be pretty potent goitrogens. I also heard about people reacting badly to some protein in rice. It would be nice if you could address those concerns. To me, most sources of protein or fat seem to be pretty harmless, but I can hardly find any source of carbohydrate that doesn’t have the potential to cause problems in already sick people, especially if eaten everyday, which is bound to happen since the variety of starch sources is so limited.

    Anyway, I’m very glad that you decided to tackle such a subject and I’m looking forward to learn more about it.

  10. I am looking forward to the rest of the series. I am also working my way through the print edition of the book, which I like a lot.

  11. Hi ben,

    Why not tell your experiences in a comment? I don’t think we need body composition changes, just an overview.

    Hi Abby,

    It seems that fiber is feeding something in your colon … rice gets digested in the small intestine.

    Hi Sebastien,

    Gut problems are some of the most difficult to heal — especially small intestinal problems — because what’s best for the body is not what’s best for the gut ailment. So you have to compromise. I don’t claim to know the optimal compromise, it may be different for every patient. But as the gut is healed and pathogens replaced with commensal species, then a modest amount of carbs should become beneficial.

  12. I wonder whether cutting out some type of food completely for a long period of time can result in the body losing the ability to digest it. For instance, if someone stops eating rice (and maybe there is nothing wrong in the first place with rice) would we still have the enzymes to digest it?

    I’m eating much fewer carbs than I used to, but I’m also making sure that if I do eat the occasional slice of bread it is a good quality, artisnal loaf of rye bread. Also, I eat/drink some probiotic foods (sauerkraut, fermented salsa, kombucha etc.) every day to keep the stomach flora in good shape.

    Very often people talk about eating this or that and I wonder not what percentage of the diet is carbs or whatever, but what the quality of that carb is.

  13. I am looking forward to more articles exploring the issue of carb deficiency. Anecdotally I developed diabetes several years after being on a low carb diet. Continuing low carb to manage the diabetes did not halt its progress. It has taken about 18 months of adding more carbs (60 – 100 gr/day)to my diet to bring my fasting glucose down by a couple of mmol and eating more carbs has also lowered my Hba1c and post meal spikes significantly. I wonder if the liver is another organ that may be effected by carbohydrate deficiency.

  14. Leone must live in an alternate universe!

    My personal experience is as follows. When I slipped into PerfectHealthDiet-mode I felt better overall, stronger and sharper (no colds/flus, and I have two young kids bringing everything home from school). However, for the full month I was on it my weight loss plateaued and I was pushed out of ketosis. No matter what I did, if I had any carbs (that’s including vegetable carbs) between 50 and 125 grams my weight did not budge at all–not up or down (stable within +/- 1 kg). I needed to go back to less than 50 grams carbs to regain weight loss and am now back in a ketotic state (and am now fighting a cold). Once I reach my ideal weight–another 9 kg–then I’ll reintroduced carbs in the 50-125 gram range. That’s my experience.

  15. Hi Melissa,

    That’s an excellent point, I think it does take time to adapt to foods that have been missing from the diet for a long time. Certainly it takes the gut bacteria time to adapt, and it may take the body a little time too to alter enzyme production, transporter molecules, etc. Malnutrition would delay the adaptation.

    Hi Leonie,

    That’s a fascinating anecdote but I would like more information about the diabetes diagnosis. What was the basis? What was your fasting blood glucose?

    I got into a “pre-diabetes” like state on very low-carb. When I had severe infections my fasting blood sugar was always getting pulled down low, but once the infections were treated my fasting blood sugar went up to 104 and if I ate starch I’d spend several hours in the 140s. This is the physiological insulin resistance that Peter has written of, and could be mistaken for “pre-diabetes.” My HbA1c was 5.5.

    Eating more carbs will definitely lower fasting glucose and HbA1c.

    That said, in my mind diabetes is a disease which involves a broken metabolism, not merely adaptations to glucose deprivation which are quickly reversed when the diet is changed.

    So I would suspect that your diabetes diagnosis was probably mistaking your body’s adaptation to chronic glucose deprivation for the actual diabetic state. Do you think that’s possible?

    Hi Poisonguy,

    Why not be on the Perfect Health Diet to get rid of the colds, and restrict calories a bit to lose weight?

  16. With only a very few very minor exceptions, I have eaten nothing but meat for just over a year. Before going on a zero carb diet, I followed a low-to-moderate carb diet for many years. My weight increased at a slow rate, as did the severity of my mood disorder. Once I eliminated those last carbs, I was able to lose the weight (50 lbs) and my mood has become so stable that I am completely off medication.

    I know of some others whose transition from LC to ZC made a tremendous difference in arthritis or asthma.

    So to me, the notion that carbohydrates are needed seems ridiculous. I would actually urge people who don’t feel optimal on a low carb diet to try an even lower one.

    That said, I am always learning, and I’m open to the idea that after some therapeutic period, people like me may eventually do better reintroducing a little more carbohydrate into the diet. But frankly, I’m not in a hurry to try it, when my weight and mood are the best they have been in a decade.

  17. This is an excellent subject, and I’m looking forward to the series. There’s a wide variety of views on this topic in the Paleo Community, and it will be great to get your take on it.

    I tried an all meat, ZC diet for 3 months, but didn’t do very well. My weight dropped too much (I was already skinny to start with) and I felt exhausted and weak most of the time. I’ve since introduced some non-starchy veggies, sweet potatoes and more recently white rice into my diet and I’m doing much better. My weight is back up into my target range and my energy level is better. I’ve had to take it slow introducing rice into my diet because if I eat too much I get bloated, but my gut seems to be adjusting.

  18. Hi Amber,

    Zero-carb is often a good diagnostic experiment to run. Plant foods are the main source of food toxins, so eliminating plant foods for a time is a good way to check whether food sensitivities are a problem. Also, lack of plant foods reduces the population of gut pathogens, so will ameliorate the symptoms of gut diseases. Finally, it produces ketosis, which gets around the effects of many chronic infections and some diseases / metabolic damage.

    So it’s not surprising that often symptoms may improve upon going zero carb.

    But that doesn’t mean that zero carb is a desirable long-term diet strategy.

    I think the next step is to experiment to try to find the specific reason a zero-carb diet is helping and to fix it. The first step would be a ketogenic diet (lots of coconut oil) with some carbs. Is the problem solved by ketones, rather than carb reduction?

    One can also try pure glucose at 400 calories per day. Does glucose replicate symptoms or does one need to eat plant foods? If the latter it suggests plant toxins / food sensitivities and/or gut infections that feed on fiber as the problem.

    Gut healing can take a long time and we recognize that removal of plant foods / fiber can be beneficial in some gut conditions – there is a cartoon to that effect in our bowel disease series.

    I would recommend that you continue trying to discover and fix your problems at their root. Zero carb is not a perfect solution and has the potential to create new problems down the road.

  19. That’s basically what I’m doing. I’m eating to satiety and letting my body decide what calorie restriction it wants. And for philosophical reasons, I guess, I won’t go with the the strict calorie counting restriction (I’m not a big fan of “calories in, calories out” theory and I’d been losing a kilo a week before I upped my carbs–results speak loudly). Plus it’s important for me to be in ketosis right now because of a potential chronic infection. So, I’m sticking to something that I know works for me. But if colds become a problem, then I’ll know it’s more than just a fluke correlation! I do believe that it’ll be easier to get into ketosis with full-on PerfectHealthDiet once I’ve reached my target weight (as set by my body) and addressed a few lingering issues (vit D levels, etc). I’ll keep you updated.

    BTW, I received the book. I’m only just starting, but it’s a great improvement from the draft, which was already excellent on its own.

  20. Long time low-carb dieter, I can attest to the fact that people’s experience varies and I would be wary of individual stories as any sort of diagnostic marker for ZC or LC diets without knowing the specifics of their meal content, individual blood panels and other activity.

    For anyone in the ZC range you must familiarize yourself with the hidden carbs in foods that often sneak up on even the strictest low carb dieters.

    to obtain under 15 grams per day would require a herculean effort of eating virtually only meat with little or no sauces, dressings or sweet fluids. i would guesstimate that people eat much more carbs per day than they believe. hence the reason why when i hear of people claiming they are low carb but cant loose weight are in fact in the 75-100 gram range upon further inquiry.

    the amount of sugar in that package of ketchup on a bunless burger and the 2 tablespoons of balsamic vinegar on a salad likely have a total of 10g of carbs, sneak in 2 or 3 during another meal and you easily approach the 15-20 gram range that provides ample glucose for the body/brain provided you eat sufficient protein/fats.

    there is little if any evidence that we could eat a pure 0 gram carb diet for any lenght of time in a regualr setting without taking an academic approach to eating that few if any people could actually do, so we should rest with the paradigm that virtually all dieters in the Zero Carb range likely eat 5-15 grams inadvertently a few times per week which skews the data sets.

  21. The Inuit may not have left medical records, but V. Stefansson was pretty good at observing and recording his observations. So much so, that he and Anderson ate an all meat diet for a full year to demonstrate to skeptics that it is a perfectly healthy diet.

    Have you considered that what you are calling carbohydrate deficiency is illness induced by too much protein? The pioneers used to call it rabbit fever or rabbit starvation. I learned about it in grade 4.

    Your claims for the liver’s capacity to make glucose are a little fuzzy. Do you have some measurement of maximum output? Or are you just going to stick with the proportional size of the liver is smaller? What are the other things a liver does? There are a few reasons that the liver might be smaller but continue to have equal sugar producing capacity.

    Have you considered the fact that blood glucose remains fairly stable, and well within the normal range in those who are in ketosis? Why wouldn’t that glucose be used? Could it have something to do with hormonal changes that facilitate using fat for energy instead of glucose?

    So far, you have impressed me with your dexterity in setting out your case, although you have offered more rhetoric than science. For instance, one or more of the many other liver functions may account for the difference in size. The most important calculation is to determine if there is a disparity between our lowest glucose needs and our maximum liver output of glucose.

    Also, what does your “12% smaller than other primates” mean? Is this an absolute measurement or is it a comparative measurement relative to body size? Since most of the brain can use ketone bodies instead of glucose, do you take that into account in your measurements? Consumption is not a measurement of need when other nutrients will serve.

    There is also the minor problem that you have asserted: “consumption of glucose is probably at least 100 calories per day above the needs of the brain and nerves” but again, consumption is not a measurement of need.

    I look forward to reading claims that are more specific.
    Best Wishes,

  22. Thank you for your reply. My diet was ketogenic most of the time before I went to zero carbs, so ketosis alone was not enough. I would be willing to try glucose to distinguish between carbs and plants; that’s an interesting idea, but I suspect it would give me intense cravings. I guess I will wait to see what you say in the rest of the series to find out why I should bother, and how much carbohydrate you think is necessary. I’m still skeptical, but I respect your work, so I will definitely listen to what you have to say with an open mind.

  23. Hi Ron,

    I’m definitely distinguishing carb deficiency from protein excess. In fact, glucose deficiency conditions are more likely if protein is deficient, as in starvation, since that further reduces glucose availability by suppressing gluconeogenesis.

    Claims are going to be fuzzy throughout this series, since this is speculative science that needs further investigation. We are generating hypotheses and trying to estimate probabilities, not declaring certainties.

    It is not well known what the limiting factors in gluconeogenesis are, but a plausible one is oxygen availability to the liver, which tends to be proportional to liver size.

    It’s clear that glucose usage by the body is not simply proportional to blood glucose levels. That is why on zero carb diets with very low glucose utilization, people often have high blood glucose levels. (See my response to Leonie above.) The signaling mechanisms which control glucose utilization are not fully understood, but obviously insulin is very important.

    The 12% smaller is taken from the Aiello et al paper and is based on scaling liver, gut and brain sizes to human body mass. Primate liver sizes plotted against body mass make a nice linear regression which gives for human body mass a liver size higher than human liver size.

    When I said “consumption” I meant consumption by cells, not consumption by the body via diet. “Utilization” would have been a better word.

  24. I will be very interested in this! I’ll send you the link when I find it, but one long-term follow-up study on epileptics treated with a keto diet seemed to show stunted growth.

    I’ve always thought that we need to define “essential” in a broader fashion. For example, even if we CAN produce all the glucose we need, is it optimal to do so? I liken this to the O3 requirements where we know this is essential, but plant sources like flax are still considered inferior as those are not in the form our body uses. So carbs may not be absolutely necessary in the diet, but dietary carbs may well be essential for optimal metabolism.

    I would dare say that the rather significant number of low carbers who experience hypoglycemic episodes are displaying a “carbohydrate deficiency”. My n=1 experience is that long term very low carbing tanks my metabolism.

  25. Hi Paul, I play with my carb intake. It varies between zero and fifty grams. I’m very interested in the subsequent posts (hypotheses) and the comments from your readers.

  26. CarbSane,

    Thank you very much, I would love to see that paper.

    I agree with all your points. As seekers after “perfect health,” we’re looking for the optimal strategy, not one that simply avoids clinical disease. We want to maximize longevity and health and fitness.

    Hans, I’m always playing with my diet too. I’m curious if things I experienced several years ago will repeat now that I have a much reduced infectious burden and much better micronutrition. Like I said to Amber, temporary zero-carb dieting can help diagnose some health conditions. I think ability to make up for a glucose deficiency is a kind of health / robustness that it’s good to optimize.

    Best, Paul

  27. CarbSane: The stunted growth in epileptics probably comes from the caloric restriction. It’s hard to grow to potential on too little food.

  28. About seven weeks ago I decided to be really strict on my diet, eliminate grains, legumes and vegetable oils wasn´t enough so I also eliminated dairy, eggs and nightshades.

    I was attempting to try to be more towards the ketogenic diet (I´ve never counted calories). I got really constipated and bloated. I have never experienced anything like that before despite my gastrointestinal problems. It was really frustrating and at times I felt just miserable.

    When I started to eat more carbs again then this problem went away although I still have GERD symptoms.

    Could the reason for this be carb restriction?

  29. Hi Anna,

    Constipation is a definite risk factor on zero-carb diets. One reason is that dehydration is very common, another is that glutathione deficiencies are common, so taking vitamin C, selenium, salt, and drink lots of water are all potential fixes.

    Some infections, esp. fungal infections, get worse on a zero-carb diet because the immune response to them is so glucose dependent. I suspect with no evidence that GERD may often be triggered by fungal infections.

    Mucus production is highly glucose dependent, as I’ll get to in this series, and it could be you lost mucus. That would account for the quick recovery after carbs were re-introduced.

    Were you taking coconut oil during the ketogenic diet?

  30. Amber: I tend to think it is also because of the necessary protein restriction required of such diets to remain sufficiently ketogenic.

    I’m not aware that deliberate calorie restriction is part of such diets. Is it? Which leads to the question/observation that most low carbers spontaneously reduce intake. And, at least this low carber finds her metabolism dialed down significantly the longer and more consistently I eat that way. So there may well be something to all the claims that LC lowers thyroid lowers metabolism (thereby requiring even fewer calories).

  31. Yes, I took coconut oil. I did take more than I´m taking at the moment which is still quite a bit. And I wasn´t that strict on my carbs either, I was never zero-carb (I like my vegetables). I was just trying to be at your version of the ketogenic diet, but I didn´t measure anything though.

    How can you know if you’ve got fungal infection and how to get rid of it?

  32. Hi Anna, Remember we don’t count vegetables as carb sources, since they may not provide much net glucose at all after digestion and gut flora interception.

    Unfortunately it’s not easy to tell if you have a fungal infection, since they’re mostly pretty innocuous. I could tell because I often had skin infections that responded to anti-fungal lotions but not antibiotics, and they correlated with colonic bloating. But there really are not good diagnostic tools, which is one reason it’s hard to get doctors to treat them, or even acknowledge they exist.

    Getting rid of them is hard too. I’m still working on mine, but I haven’t had a skin manifestation since the first month of antibiotics last year.

  33. Amber, CarbSane,

    Many clinical implementations of the ketogenic diet are too low in protein (we recommend carbs + protein > 600 calories, so on zero-carb that’s a lot of protein) and also deficient in other nutrients. I would expect stunted growth to be due to some kind of deficiency, whether protein, micronutrition, or total calories — but probably not total calories if the patients are actually adhering to the diet.

    The thyroid issue is complicated but I haven’t experienced lowered metabolism on low-carb diets. My body temperature has however gone all over the map depending on micronutrient status, macronutrient ratios, and infectious burden. I spent many months over 100 degrees at one point despite a subclinical hypothyroidism indicated by elevated TSH. Now my body temperature is normal all the time.

  34. I had some starchy vegetables like carrots and sweet potato, but I guess it wasn´t enough. It got better when I started to eat some bananas and some honey.

    did antibiotics help your fungal infection then?

  35. Paul, about year ago, before finding your website, I cut down drastically on carbs and lost about 10 lbs in 6-7 months, but for the first time in the 75 years of my life, had bloating and gas. Since following your diet, the gas and bloating have subsided a bit, but I’ve lost only about one and half pounds in 2-3 months.

    I know you said to be patient, but it is frustrating!

  36. Hi Anna,

    The antibiotics caused it to flare up, I’ve been gradually trying to get rid of it since.

    Hi erp,

    I emailed you separately. I’m glad the gas and bloating are down a bit; gut issues are slow to resolve from diet alone so it’s not a surprise that progress there is slow. On speed of weight loss, I didn’t know that was your goal. There are various adjustments that can be made for more rapid weight loss.

  37. That makes more sense, I misunderstood.

    So do you think in the long-run your diet can resolve most problems with fungal infection?

    At least at the moment the GERD symptoms are manageble so I hope I´m on the right track.

  38. I think so, but I am constantly trying to find ways to help. Right now I’m snacking on raw cranberries, since they’re in season. A good anti-yeast food.

    Presumably one issue is the loss of commensal bacteria during the antibiotics, and I may not yet have enough bacterial species back to displace the fungi. Short of a fecal transplant, it just takes time.

  39. In people with insufficient insulin to inhibit hepatic glucose production (untreated type 1 diabetics), blood glucose is extremely high. This suggests that the human liver is capable of producing more than enough blood glucose for the body’s needs.

  40. Hi Paul,

    I’m very excited to read this series. Like many of the other posters I am on a LC Paleo diet. I struggle with the amount and type of carbs to include. Personally I have oberved three kinds of reactions to eating starchy carbs. Certain kinds of fruits and veggies (apples, cauli, carrots etc) cause my face to flush within 20-30 minutes of eating them. Then within an hour I have joint inflammation that is most noticable in my hands, feet and ankles. This is often accompanied by a splitting headache. Because of this I try to limit carbs to about 50 g from dried fruit, berries and dark chocolate.

    I’ve tried fat laden sweet potatoes with butter and coconut oil. Those don’t seem to cause face flush, but they do cause joint swelling within an hour of eating. With rice I have face flush, joint swelling and the next day I have lower back pain and a stiff neck.

    On the other hand carbs from a few dates wrapped around a pat butter does not cause joint swelling or back pain or headache.


  41. this is gonna be a gooooooood series. so glad i found this blog. going to the bookstore after work to hopefully find your book and if not i am ordering it tomorrow and reading ASAP

    given my situation, recovery from anorexia. i wound up in relapse after a year long zero carb diet. now, on paleo/primal i have experienced the keto-fatty acid bruning metabolism and the carb-burning metabolism. two very different feelings, and in my opinion two verrry different subjects.

    the keto induced fasting blood sugar and the carb burning induced blood sugar, fasting, would signify two totally different health determinants, no? one would be the prediabetes condition you mention, and which i suffer from myself, as a evolutionary adaption? just a thought.

    theres no doubt carbs make people gain and lose weight, but i am confused about the leptin and socs3 regulation, the hypothalamus and the HPA axis in relation to a keto vs a carb diet.

  42. Nigel –

    This is a new one for me. Is it the case that:

    1. On a zero-carb diet or long fast Type I diabetics develop and maintain excessive blood glucose?

    2. Type I diabetics never develop hypoglycemia except when taking insulin?

    I had always thought that Type I diabetics developed high blood glucose from a combination of hepatic production and dietary carbs.

  43. @CarbSane
    I’m sorry I don’t have a primary source at the moment, but Emily Deans says “ketogenic diets were calorie restricted to just 75-90% of what would be considered a child’s usual calorie intake”. [http://evolutionarypsychiatry.blogspot.com/2010/08/your-brain-on-ketones.html] I haven’t seen reference to restricted protein. I hope you find the link you were thinking of.

  44. Great series Paul. I would like to add a datum point re my experience. I started LC diet because moving to a more “healthy” diet (60% carbs, my doctors advice) clearly produced bad results ie worsened periodontal disease & flatulence/loose stools. Other than that, I was symptom-free and normal weight. On 50g carbohydrate, 2 months into experiment, I developed strange joint aches, a new aversion to hard cheese & nuts, some incipient constipation problems, and lost unintended weight. However, gum disease and other biomarkers showed significant improvement. I then increased carbs to 100g/day and the joint aches have greatly diminished, weight has increased (+5lbs) and BM’s somewhat improved although I need about 15gm fibre/day. This improvement took about 6 weeks to be consistent; it is now 5 months into the LC regime. I have not dared go back to cheese and nuts. Of course, the symptoms/improvements may have been entirely due to timing alone, as adaptation no doubt plays a role. I wonder whether I should attempt to lower carbs in the future.

  45. Paul, here is a great find from LynMarie Daye of Adipo Insights: http://bja.oxfordjournals.org/content/85/1/69.full

    It is quite eye-opening on the role of insulin, etc. and its apparent predominant inhibitory role.

    That said, just because T1’s are capable of overproducing glucose in the short term, the life-expectancy of an uncontrolled diabetic of this type pretty much limits our ability to assess whether the liver can keep this up in the long term.

    The liver has many tasks, and if one pre-occupies it with one, another can suffer. I’ve had conversations with T2’s and borderlines who will drink before a FBG test because metabolizing alcohol will suppress gluconeogenesis. Indeed there are any number of alcoholics who suffer from hypoglycemia for the same reason.

    So, even if in the short term our livers can make all the glucose we need, this does not rule out that over the long haul it may tax our livers to rely on them completely.

  46. Thanks, CarbSane, I was just about to post the same thing. Nigel sent me a link to that paper.

    The high fasting hyperglycemia in diabetics was observed only in short fasts (< 24 h) and the glucose was obtained from liver glycogen, not gluconeogenesis. I'm still looking for papers on what happens to Type I diabetics on a long fast, but I'm pretty sure it's not hyperglycemia. I don't believe that gluconeogenesis in the liver is sufficient to satisfy the body's glucose needs. Even with glucose conservation due to ketosis, on long fasts people develop coughs due to insufficient mucus. Insufficient mucus on glucose deprivation is going to be a primary theme of this series.

  47. Nigel, I know very little about diabetes, but isn’t it possible that the liver is making small amounts of glucose, but because the body’s tissues are unable to withdraw glucose from the blood, glucose builds up there?

    In other words, I don’t see how we can conclude anything about the rate of production without also knowing the rate at which glucose leaves the blood.

  48. Nigel, nevermind, I see that the paper linked by CarbSane answers my question. 🙂

  49. Hi Paul,

    “I would like more information about the diabetes diagnosis. What was the basis? What was your fasting blood glucose?”

    I was diagnosed following a GTT which showed a prolonged spike of 14mmol (252). Subsequent GTT’s following a 3 day carb load still spiked at 12mmol. My fasting BG was around 4.2 – 4.6 mmol prior to lowcarb. During lowcarb it was around 7.1 mmol – 8 mmol. Nearly two years after adding more carbs back it is down to mid 5 to mid 6 mmol. My HbA1c is down to 5.8 from 7.5. so still not in normal ideal range.

    “So I would suspect that your diabetes diagnosis was probably mistaking your body’s adaptation to chronic glucose deprivation for the actual diabetic state. Do you think that’s possible?”

    You may be right Paul. If that is the case though, it means that the carb restriction has caused permanent metabolic damage. A carb loaded meal still pushes me up above the 12mmol range.

  50. Hi Leonie,

    I’ve never heard of such an extreme reaction to a low carb diet before.

    I don’t understand what happened. But I’m glad a healthy amount of carbs are helping. The amount you’re eating now is right at what we consider optimal. But I don’t really know if that recommendation is optimal for you.

    Your case is so unusual, we would like to try to understand it. Keep us posted on your experiences, maybe some of our smart commenters can help figure out what happened.

Leave a Comment

NOTE - You can use these HTML tags and attributes:
<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>

This site uses Akismet to reduce spam. Learn how your comment data is processed.