Is There a Perfect Diet?

We’ve begun blogging at Psychology Today, and I figured I’d start with an introduction to our diet. This is a slightly altered version of our first post there. — Paul

“All healthy persons are alike; each unhealthy person is unhealthy in his own way.”

If Tolstoy were a diet-and-health blogger, this might be how he would begin.

All healthy persons are alike

The composition of cells hasn’t changed much since the origin of complex multi-cellular life about 500 million years. Apart from water, the major components are fatty membranes and proteins. More than half the proteins are glycosylated – bonded to glucose-derived carbohydrates. These compounds – fats, proteins, and glucose – are the basic “macronutrients” needed by cells. In organisms, these cells are supported by an extracellular matrix composed of glycans and proteins; this matrix is mineralized in bones and teeth.

Why do animal species differ in their nutritional needs? Actually, nutrient needs differ remarkably little across the animal kingdom. This is why animals comprise “food” for one another: the ingredients of all animals are the same, so one animal nourishes another.

It is also why breast milk varies little across all mammalian species: the composition of cow’s milk is not much different from the composition of lion milk, for instance – or human milk for that matter.

Human nutrient needs differ from those of other mammals chiefly by virtue of our larger brains, which are rich in omega-3 fats and require extra glucose for energy. But large brains only modestly tweak the needed macronutrients: compared to other mammals, an extra 10-15% of calories as glucose, and an extra 1% of calories as omega-3 fats, are more than sufficient to nourish a human.

If all animals are alike in their nutrient needs, why are diets so different? Why don’t lions sup with lambs?

It turns out that what differs among the animals is the composition of the digestive tract. Animals have evolved digestive tracts and livers to transform diverse food inputs into the uniform set of nutrients that all need. Herbivores have foregut organs such as rumens or hindgut chambers for fermenting carbohydrates, turning them into fats and volatile acids that can be used to manufacture fats. Carnivores have livers capable of turning protein into glucose and fat.

When we look past the digestive tract at what nutrients are actually delivered to the body, all mammals obtain a remarkably similar set of nutrients. By calories, mammalian diets are always composed of a majority, typically 50-75%, of saturated and monounsaturated fats (including the short-chain fatty acids produced by fermentation of fiber); a mix of carbohydrates and protein, usually totaling around 25-40%; and a modest amount of polyunsaturated fat, typically less than 10%.

If diets differ because of digestive tract differences, we should expect the same pattern to recur in humans. All humans have the same nutrient needs, but our optimal food intake may vary if our digestive tracts differ.

In fact there is evidence for variations in digestive tract structure among human populations. Melissa McEwen has summarized evidence that Africans have slightly larger colons, suggesting a slightly more plant-focused evolutionary diet, and Europeans have slightly smaller colons, suggesting a more animal-focused evolutionary diet [1, 2].

Longer colons allow more fermentation of plant fiber, but they don’t dramatically change macronutrient ratios of the diet. Across human populations, the optimal human diet probably doesn’t vary in any macronutrient by more than 5% of energy or so.

So there is little support for a “blood type diet” or “metabolic type” with significantly different food needs. All healthy people can and should eat a similar diet – one that approximates to our body’s nutrient needs.

Each Unhealthy Person is Unhealthy in his Own Way

What are the causes of ill health? We believe there are three fundamental causes of ill health: malnutrition, toxins, and infectious pathogens.

There are dozens of elemental nutrients – vitamins, minerals, and biological compounds – whose absence in the diet can impair health. Many thousands of toxins, totaling several grams in weight daily, enter the human body; as Bruce Ames and Lois Gold have shown [3], plants make a host of natural food toxins, and food storage and cooking create more. Finally, we are continually exposed to microbes; there are probably hundreds of pathogens capable of establishing human infections.

It doesn’t take a mathematician to see that there myriad possible combinations of malnutrition, poisoning, and infection. The causes of disease are legion; it’s no surprise that the manifestations are so various. The number of possible combinations of disease causes is more than the number of humans. To a first approximation, every disease is unique.

Each combination of causes will affect the optimal diet in a different way. People who are malnourished will benefit from getting more of the things they are malnourished in, and perhaps less of others which balance those – as reducing zinc may help someone who is copper deficient, or reducing omega-6 fats may help someone who is omega-3 deficient. People exposed to toxins may benefit from an extra dose of toxin-metabolizing nutrients. People with infections may benefit from diets which starve pathogens of needed nutrients, or which support immune function. People with gut dysbioses may benefit from removing or reducing whole classes of foods – starches, fructose, FODMAPs, fiber, even protein.

Infections can make a big difference in the optimal diet. Ketogenic diets, which starve the brain of glucose but feed it with small molecules derived from fats, are highly effective against bacterial infections of the central nervous system, since bacteria depend on glucose metabolism. But hepatitis B and C viruses can utilize the process of gluconeogenesis – manufacture of glucose from protein – for their own benefit, so people with hepatitis benefit from higher carb diets.

Other pathologies disrupt the ability to handle certain nutrients. Diabetes is characterized by an inability to secrete insulin, and diabetics usually benefit from low-carb diets. Migraines, like epilepsy, may be caused by genetic or other impairments to brain glucose metabolism, and can often be cured by ketogenic diets, as several of our readers have discovered.

With ill health, the optimal diet often changes. Sick people often have to tweak their diet, and the nature of the change varies with the nature of the pathology.

Diet Can Be a Diagnostic and Therapeutic Tool

Precisely for this reason, diet and nutrition have a valuable place in the healer’s arsenal. A sick person’s response to dietary changes can be informative about the nature of his pathology.

For instance, ketogenic diets are therapeutic for bacterial and viral infections, but can feed protozoa, fungi, and worms (which have mitochondria and can metabolize ketones). Response to a ketogenic diet can help expose the nature of an infectious pathogen.

Because neurons are dependent on glucose or ketones for energy, any pathology which disrupts glucose utilization will cause neuronal starvation, and neurological and psychological distress, which can be relieved by provision of ketones. A well-designed, nourishing ketogenic diet may often ameliorate psychiatric and neurologic disorders.

Dietary tactics can help prevent as well as treat disease. For instance, fasting upregulates autophagy (“self-eating”), the cellular mechanism for recycling damaged or unnecessary components. But autophagy is a central part of the innate immune system; it is how cells destroy invading microbes. Intermittent fasting as a regular practice helps keep the body infection-free, and during intracellular infections refraining from food is often a helpful strategy.

For some pathogens, on the other hand, providing the immune system with plenty of food is usually a better strategy. “Feed a cold, starve a fever” – or is it the other way around? Your body will usually tell you what to do, suppressing or promoting hunger as needed.


There is no one diet that is perfect for everyone, but that is mainly because not everyone is healthy.

Fortunately, healthy people are generally alike in their dietary requirements. We can identify a diet that is very good for nearly everyone, and can tweak that diet in various ways to help diagnose and heal diseases. That is the goal of our book, Perfect Health Diet, and of this blog.


[1] Katsarski M, Singh U. [Anatomical characteristics of the sigmoid intestine and their relationship to sigmoid volvulus among the population of Uganda and the city of Plovdiv, Bulgaria]. Khirurgiia (Sofiia). 1977;30(2):159-63.

[2] Madiba TE, Haffajee MR. Sigmoid colon morphology in the population groups of Durban, South Africa, with special reference to sigmoid volvulus. Clin Anat. 2011 May;24(4):441-53.

[3] Ames BN, Gold LS. Paracelsus to parascience: the environmental cancer distraction. Mutation Research 2000 Jan 17; 447(1):3-13.

Leave a comment ?


  1. Paul, what a great post! You gave me much food for thought, as I have suffered severe migraine since age 11. It improved greatly when I moved from Wisconsin to southern Nevada (stable weather) and has virtually disappeared since I starting following an ancestral diet. I had wondered why I don’t seem to relish starchy foods as much as many others and now I wonder if that relates to this post. I do eat lots of non-starchy vegetables and moderate fruit along with my meat/fat but the only tuber I really enjoy is rutabaga.

    Hmm. Maybe my body was trying to tell me something all along!

  2. amazing post!

  3. Hi Paul
    Great post. I do have a question. You say: “For instance, ketogenic diets are therapeutic for bacterial and viral infections, but can feed protozoa, fungi, and worms (which have mitochondria and can metabolize ketones). Response to a ketogenic diet can help expose the nature of an infectious pathogen.”

    Can you clarify what response to a kerogenif diet suggests a bacterial/ viral infection and what response suggests a fungal infection?

    Thanks much.

  4. Hi Nance,

    I’m glad your migraines are better! Ketosis can sometimes be wonderful.

    Hi Radhika,

    If you get better / feel better on a ketogenic diet, it’s more likely to be a bacterial infection; if you get worse, it’s more likely to be a eukaryotic infection.

  5. As the fuel mixture used by our muscles varies hugely depending on what we’re doing with them, I’d say that there isn’t a perfect human diet.

  6. Hi Paul,

    I have repeatedly read that you state the following:

    “For instance, ketogenic diets are therapeutic for bacterial and viral infections, but can feed protozoa, fungi, and worms (which have mitochondria and can metabolize ketones).”

    It makes sense, but I found this study:

    It seems that ketone bodies can fuel the growth of M.tuberculosis and Staphylococci, inhibiting the bactericidal effect of lactate. This despite being intracellular pathogens. It might relate to the well known fact that M.tuberculosis has a lipid-based metabolism.


    “However, both 3-OHB and AcAc dose-dependently inhibited superoxide anion (O2-) production, measured by using cytochrome c. ”

    Other interesting papers:

  7. Hi Nigel,

    Thanks. Athletes have special requirements for glucose. Interesting data in your post!

    Hi Lucas,

    Thanks much, interesting papers. I have to account for effects on immune activity as well as for effects on pathogens and autophagy. Leukocyte activity / phagocytosis is predominantly an extracellular activity, so the intracellular/extracellular distinction may be as important as the prokaryotic/eukaryotic distinction.

    It looks like more reasons to make ketosis intermittent rather than continuous.

  8. Hello Paul,

    Congratulations on the Psych Today gig! I am very happy that a broader audience will get exposed to PHD given I think PHD rocks!!!

    Regarding healthy individuals and this comment above – “healthy people are generally alike in their dietary requirements”. On page 170 of PHD, you reference the Kitavans and I agree that their staples are totally PHD compliant. Obviously their macronutrient composition is grossly different from PHD recommendations.

    I realize that “the nutritional content of your diet is different from the nutritional content of your food” (page 11 PHD). I have seen enough evidence to suggest that for “unhealthy” individuals, that LC diets might have therapeutic benefits and even with the inclusion of safe starches, PHD is still LC.

    However for “healthy” individuals, I am struggling to see the need for deliberate carbohydrate restriction. This is not argument against LC that I am making (far from it) since healthy individuals can also choose to be LC if they so desire and thrive.

    If we have to pick an optimal macro ratio, then the PHD recommendations make sense based on the evidence you have provided, but the tolerance about these averages is so huge that it brings into question the relative importance vis-a-vis toxin avoidance and micronutrient needs, which can be satisfied on a high carb diet as well.

    I raise this only because the fact that the implementation of many Paleo diets is empathetically LC does make it a requirement per se. I still consider myself a PHD-er, my macronutrient heresy notwithstanding 🙂

    Again, congratulations to you and Shou-Ching!

    Warm regards,

  9. Hi Aravind,

    Thanks much, it will be interesting to reach a broader audience. I’m glad to see you’re preparing us for the “too low carb” criticism.

    I basically agree with you:
    1) Healthy people can handle a wide range of macronutrient intakes.
    2) There’s no direct evidence that high carb diets, if the carbs are “safe,” are dangerous.
    3) “Deliberate” carb restriction is probably unwise, because the reward center of the brain evolved to make his healthy, and the optimal amount of carbs is probably close to the amount that we find satiating/satisfying. So, if carbs tempt us and we have deliberately avoid eating them, we’re probably eating too few.

    However, I think a few hints point to low-to-moderate carb consumption as best:
    – The composition of breast milk and of animal diets;
    – Counting up the nutrient needs of the human body.

    The issue of “relative importance” is really one of robustness. Tolerance for deviations may be huge when one is healthy, but an infection might change that status in days.

    I also consider you a PHD-er, deviation in one element like carb percentage is not decisive. We try to educate and provide a strategy for personal diet design, not dictate specific nutrient amounts.

    Best, Paul

  10. Hi Paul and community,

    Great post! About the response to ketogenic diets…

    You mentioned how ketogenic diets might not be good if you have a protozoa, fungi or worm problem because those pathogens can metabolize ketones. So, as a kind of diagnostic test, if I tried the intermittent fasting (or maybe even a 24 hour fast) and then periodically during the fast checked for ketones (Ketostix urinalysis reagent strips), would that give me any indication as to whether or not there was a eukaryotic infection of some sort?

    Here is my thought process: I was thinking that if I fast long enough to ensure that I would most definitely produce ketones, then check ketone presence with the reagent strips, then I might be able to translate the findings from the reagent strips like this:
    – if no ketones (or only trace amounts) present, strong possibility of eukaryotic infection (because they are metabolizing the ketones, so it will appear as if I didn’t make any ketones) ???
    – if ketones are present in more substantial amounts, then there probably isn’t a eukaryotic infection

    Would that work at all?? (Remember, I’m waaaaaay out of my realm of expertise.)
    Or does it take much longer than that to actually produce enough ketones to show up in urine?
    And, do the protozoa, fungi or worms not metabolize enough ketones to drastically drop your body’s ketone level?
    Also, I don’t know if diabetics produce or deal with ketones differently, so maybe the test wouldnt show me much anyway.

    In any case, I will try to get a stool test ordered from metamatrix to see what’s going on in my gut. (I thought the diarrhea was gone, but again today and once a few days ago. I guess it could be a million different things, it’s just hard to know where to start.)

    Any help or ideas are greatly appreciated.
    Thanks again so much!

  11. Paul,

    This is a really enlightening post.

    Do you think a ketogenic diet would help with skin problems or would it more likely make it worse? How about 16 hours of fasting followed by an 8 hour window of PHD eating.

    Why do you think following a low histamine diet seems to improve many skin issues as Chris Kresser reports? Could there be some connection between histamine and a common pathogen which causes skin problems?

    Which pathogens are most commonly associated with reoccurring skin issues? Fungal? Bacterial? Virus?


  12. Thanks for the response Paul. I don’t consider PHD “too low” in carbs at all (hope you didn’t think I was being critical) and the inclusion of safe starches is a very important tenet that differentiates it from other approaches where starches are the devil!

  13. Hello Paul,

    Great book…it’s good that you get down to the nitty gritty in the chemistry on the breakdown of fats ,carbs and protein. In the research I’ve done on amino acids, one thing stood out to me, wild animals (deer, elk, bison, ect.) have a higher amino acid content than today’s meat we eat for protein intake.

    Also the fat content is lower in wild game animals saturated and especially pufas’s. So considering the amino acids of the protein with much more quality and the fats being lower, would this change the ratio of protein to fat you suggest?
    Glad that I found your book and blog. Have learned a lot through everyone’s discussions.


  14. Nice use of Anna Karenina. I would even dare say the paraphrased quote might be more accurate than the original.

  15. Hi Paul
    Loved your book and have shared with my family. Thank you so much for all you do. I am reading comments about Reynauds syndrome on the site. You have suggested coconut oil and iodine. How much of each is required? Thanks s much for your reply

  16. I’ve always found it interesting that breast milk really doesn’t vary much between mammals. Lots of health blogs have talked about how breast milk is like the perfect food (or that it gives us the macro ratios we need). The only thing I know 100% of breast milk is that it nourishes and grows babies. If anything, milk in any form is not the perfect food. Milk is meant to grow us — not too keep us alive as long as possible. It is way too high in factors that promote the formation of IGF-1, and therefore is pro-aging. I always think health bloggers should distinguish between growth and longevity diets because I bet they are mutually exclusive.

  17. Hi Paul, Great book and blog. Am particularly interested in the comment regarding Hep B and C virus and a higher carb diet. Can you elaborate or give me a link to further info on this topic.

  18. Hi Donn,

    The papers I recall on hepatitis viruses benefiting from gluconeogenesis don’t jump out at me at the moment, but here’s one:

  19. What an excellent, clarifying post! It made the entire topic of diagnostic dieting make much more sense and was a very clear, yet not overly technical, explanation.

  20. Hi Paul,

    Regarding “Your body will usually tell you what to do, suppressing or promoting hunger as needed.”

    Me and my son has had fever and mildly sore throats for almost a week. We’ve had no appetite at all. Many parents and most grand parents think that one really must eat and therefore keeps nagging about food when the poor child (young or adult) really does not want any food. In a situation like this, I guess it’s ok not to nag and let the sick eat as little as she likes? I think it’s a little weird that the appetite is lost, but maybe it wants autophagy? I was thinking it might be because of the sore throat and not wanting irritating stuff there, but the urge for food should be stronger than that. And the pain comes from the brain and not the tissue (I suspect, from reading blogs like Todd Hargrove), so why does the brain think that it should feel irritating to eat food? Could that really be autophagy again, or is it because it means less nutrients for the pathogen in the throat or what do you think? The head keeps spinning with thousand questions and it’s a nice feeling. It’s frustrating though not to be able to get them all answered 🙂

    There are a lot of calories in the body one should be able to use during starvation so I assume there are other nutrients that limit for how long one can survive starvation. What nutrients deprives the body most quickly and are the biggest limits for how long one can survive not eating (but still drinking water).

  21. Hi Tim,

    Yes, I think the loss of appetite is part of the immune response and you should trust it. I would recommend eating little until your body tells you it’s time for food.

    I’d still try to get normal micronutrients however. Therefore I’d eat nutritious fluids like bone broths and vegetable soups made from bone broth or chicken broth, maybe a few spoons of yogurt with a multivitamin, things like that. Tea, or herbal concoctions like ginger root in water, can also provide a bit of nourishment.

  22. Hi Paul,

    Where should I be getting my green tea from these days? I know in the past you suggested avoiding China due to pollution and suggested Japan instead. But after the nuclear reactor situation there, is green tea from Japan safe? I’m no longer sure where I should get my green/white tea from. Are there specific places I should avoid or seek out? And are there specific products/brands you recommend, on Amazon perhaps? Thanks…

  23. Hi Tea,

    I think Taiwan and Japan are both good. The tea growing regions of Japan are in the southwest, Fukushima is in the northeast, and the wind blows out of the west, so blows the radioactivity to the east and the Pacific. Tokyo is at risk but not the tea-growing regions.

    If you look in our “Green Tea” post ( and the comments, there are suggestions for brands and places to buy.

  24. Hello Paul,

    Wild animals (deer, elk, bison, rabbit, etc.) have higher amino acid content than today’s meat we eat for protein intake.
    Also the fat content is lower in wild game animals. So considering the amino acids the protein with much more quality and the fats being lower, would this change the ratio of protein to fat you suggest?
    I’m having a difficult time getting the ratio of fat you suggest even adding in eggs and cooking everything in coconut oil and butter.
    Do you think it is wise to just eat some pure fat of some kind to get fat ratio up?
    Any healthy suggestions appreciated
    Thanks Melvin

  25. Hi Melvin,

    There’s no need to eat pure fat.

    Re the meat, judge by taste. If meat is lean, then fats should be added as a sauce or accompaniment — eg guacamole with chicken breast. Meat with the right ratio should taste moist but not super-fatty.

    The other way to get the fat:protein ratio up is to eat carbs accompanied by fat. Eg, a potato with butter, rice and vegetables with egg yolks.

  26. Hi Paul,

    I have lost 50 pounds this past year by exercising more and eating a low carb diet (with coconut oil, cod liver oil, and fermented foods), and I have another 50 still to lose. During the first 8 months 40 pounds came off with little effort, then it slowed way down and in the last 4 months I have only lost 10, and those were very hard earned. I have also noticed hair loss from my head and legs, and blurry vision at times.

    I would like to lose the rest of my weight using your diet, but every time I try to raise my carbs even a little I gain weight shockingly. Is this normal, or have I ruined my thyroid/adrenals? How can I raise my carb level yet continue to lose weight?

  27. Thanks Paul,

    One more question, off topic. My mom recently overcame breast cancer (she had chemo and radiation). She had healthy bone density in the past but now her bone density levels are extremely low to the point that her Dr. is recommending a “reclast” infusion into her bone(s). Any idea as to the safety of this infusion? She excercises regularly with weights and cardio but this hasn’t helped her bone density, nor has calcium supplementation. I recently got her on 180mcg of MK-7 a day from Natto (from your supplements links) and am hoping this helps. Do you think that’s a high enough dosage for it to have an impact? Also, are there any suggestions in terms of supplements or dietary advice/foods that may help improve bone density? Thanks again Paul, you are the man!

  28. Hi Meli,

    The hair loss is a sign of hypothyroidism, which is aggravated by being too low carb. Blurry vision could be several things, but dry eye from being too low carb is most likely.

    I think you have no choice, you need more carbs.

    I wouldn’t focus on weight yet, focus on your health. Keep omega-6 as low as possible, take micronutrient supplements to assure good nourishment, eat soups made from bone broth and seaweed or shellfish.

    I think if you nourish yourself properly your weight will stabilize at a higher level and then start decreasing again.

    Best, Paul

    Hi Tea,

    I don’t know anything about reclasts. I would suggest researching it carefully including feedback from people who have had it. Forums are helpful, eg

    If there’s no immediate danger then I would give natural methods some time, including supplementation D/A/K2, magnesium, selenium, zinc, copper, low-level iodine, B12, vitamin C, MSM, and plenty of bone broth soups. Sufficient protein and carbs.

    180 mcg should be enough K2 but there’s a Life Extension mix with K1/MK-4/MK-7 that has over 1 mg. I take that 2x per week, she could take it more frequently, it’s very safe after a short adaptation period.

    It can take weeks to months for stem cells to proliferate, so I wouldn’t rule out recovery just because it’s been proceeding slowly.

    Best, Paul

    PS – Here was an old post about how slow bone healing can go when you’re missing nutrients:

  29. Hello,

    just started reading your blog, and really enjoying it. I have a question to this article though: you posit that the nutrient needs of all healthy individuals are the same. Whilst I don’t disagree that this is possible I feel that this is something that would require a bit more validation, given the vastly different diets that certain “natural” tribes are eating (Inuit and the like).

    My point is – there could be a genetic difference in metabolism, or there could be a priming effect either in the womb or as a child, that could make that different people need different diets. I am not saying that there is, it is just that I would think that this needs some evidence rather than just an assertion.

    Thanks again for the great blog!

  30. Paul,

    Have you and, other health bloggers read SOPA?

    The bill that the government has up to stop piracy
    on the Internet?

    I just clicked on a site to read SOPA. The first
    thing that stood out in my mind was

    SEC.105. Immunity for taking voluntary action against
    sites that endanger public health.

    I do hope this is stopped!

    I feel like Big Pharma is behind this one. As more
    and, more of us are learning healthier alternatives
    to drugs and, procedures.

    I pray this goes viral and, the public can protect
    it’s right to know the truth!

  31. Very helpful – thanks Paul!

  32. Paul,

    Any thoughts on almond flour brands and whether I need to splurge for organic? If we are in pretty good health, can’t our bodies get rid of any toxins that may linger if I go regular vs. organic? My main concern is whether or not I need to spend the extra money on buying organic almond flour vs. just going with regular almond flour…


  33. Hi Thor,

    There are, in fact, developmental effects in utero and early life that shape people’s response to diets – make them more or less efficient/thrifty, for instance.

    But these effects don’t change basic biology, so they don’t make a big change in design of the diet.

    Hi Betty,

    It’s a travesty of a bill. I doubt Big Pharma is behind it, but it’s clearly a power grab, and it’s likely to be used for the benefit of the most politically well connected interests. Hopefully it will stay dead.

    Hi Tea,

    I’m not aware of any special advantage to organic almond flour, but I’ve never looked into the matter.

    We don’t use almond flour ourselves (we bake with rice flour / potato starch / tapioca starch) so we’re not that informed about it. But I think on most goods environmental toxin levels are low.

    Best, Paul

  34. I saw Dr. Jaminet’s recent interview with Dr. Mercola. Very thought-provoking!

    It’s my understanding of the PHD, that people should eat some dense carbos. In the interview, Dr. J points to rice, potatoes and sweet potatoes, one pound daily if I remember correctly.

    Now, where does fruit fit in? It is relatively dense compared to fibrous vegetables. Many are hi-glycemic. How much fruit would be “safe?” How much above the “one pound daily” of starchy carbos (rice, potatoes, etc.)?

    Great blog!


  35. Hi Michael,

    In general, our “safe starches” have 300 to 600 calories per pound and fruits and berries have about 200 calories per pound. We recommend getting 400 to 600 calories per day.

    So maybe 3/4 pound safe starches and 3/4 pound fruits, or a bit more safe starches and a bit less fruit, would be good. Vegetables don’t count.

  36. Hi, Paul. I have read your book and have been reading all I can on this site. Thank you so much for sharing information with everyone.

    I have been diagnosed with Hashimotos thyroiditis. I am currently on 45mg Armour. I have other autoimmune stuff going on. I have dsDNA antibodies, and my rheumatoid factor is above normal, but not crazy high. I think it has been in the 20’s and 30’s. My general symptoms are joint and tendon pain (mostly in the hands and feet), my hair is falling out, chest pains, brain fog (I forget simple things easily), tiredness, and probably some other things I am forgetting. I have not been diagnosed with either lupus or rheumatoid arthritis. I see a rheumatologist next month.

    I am also seeing a preventative healthcare doctor, and am recieving peptide shots there. Have you heard of this? They are quite expensive. I have noticed no difference from this.

    I have had food allergy testing, and they have had me off of some foods that I have tested positive for. I eat no gluten, wheat, dairy, but have not been consistent with this (example – Christmas). I am now commited to avoiding all of that stuff, and have started to do the best I can with your diet (but avoiding the things they have told me to avoid).

    My question is about the fasting and trying to figure out the possible cause. How long would you continue doing short fasts (16-36 hours) before you determined whether it was making a difference? I am low-ish body fat as I am a former figure competitor. Yes, I am also kind of wonderring if that has contributed to my condition. My point being…I don’t have excess body fat to support fasting, necessarily. But I am trying to push in those calories 1200-1700 during the 8 hour period.

    I am also trying to figure out if it could be viral/bacterial/fungal. My focus right now is maybe yeast.

    I know this is rather rambling, but if you have any thoughts I would be so grateful. I am very stressed and sad about living my life with a chronic disease. I REALLY do not want to go on traditional meds.


  37. Hi Ali,

    First, if you’re hypothyroid to the point that hair is falling out, and you’re slender, I would not fast. In your condition it’s usually best to be well nourished and avoid stressing the body.

    Don’t restrict calories and don’t try to be unusually lean.

    I have not heard of peptide shots.

    Personally, I believe that occult infections are usually the cause of the autoimmunity, and that it’s more helpful to treat the infections than to suppress immunity, which relieves symptoms but can exacerbate infections over time. So personally I would try antibiotics, and would also chase diagnostic testing for pathogens, which is unfortunately too often inconclusive but occasionally turns something up.

    You could try supplementing with detox aids like activated charcoal or bentonite clay, that often relieves symptoms.

    It’s an experimental process and generally takes some time, but many people with similar profiles do find relief. Please keep us posted.

    Best, Paul

  38. Hello,

    You said “Intermittent fasting as a regular practice helps keep the body infection-free, and during intracellular infections refraining from food is often a helpful strategy.”

    I was just wondering how often you recommend fasting and for what length of time? (and any other details concerning the fast)

    Thank you,

  39. Hi Kyle,

    By intermittent fasting I generally mean a 16 hour daily fast, confining all food to an 8 hour eating window, and doing this daily.

    Alternatively, one can do longer fasts less frequently. A 23-hour fast (dinner one night to dinner the next) might be done once a week. A 36-hour fast (dinner one night to breakfast the second day) once every two weeks.

    However, it all depends on health. The healthier and more well nourished you are, the better you will tolerate fasting. If fasting is a struggle, wait until you are healthier.

  40. Hi Paul,

    I have chronic Hep B. We had some comments with each other on another post of yours some time ago. From memory we came to the conclusion that fasting for someone with Hep B was not a good idea as the evidence we were discussing at that time pointed to the HBV virus taking advantage of the autophagy process which happens during fasting. My liver enzymes increased more or less at the time I was doing intermittent fasting but I stopped that practice because it just did not make me feel good (luckily!).

    Looks like this little sucker has multiple ways of taking advantage of metabolic processes in the body (via autophagy, and now gluconeogenesis) to help it replicate.

    So the moral of the story for Hep B affected people – no fasting and consume enough carbs to keep the body from going into gluconeogenesis territory? (oh, and be sufficiently nourished). Would you recommend carbs be somewhere in the 30%-40% range rather than your “standard” 20%-30% range?


  41. Hi David,

    Yes, I think 30-40% should be pretty good for hepatitis. You could go as high as 40-50% if you like, but 30% should be fine.

    Best, Paul

  42. Hi Paul-
    Is it known whether intermittent fasting (IF) has effects on e.g, neurotransmitters? I’ve been consistently IFing since reading your book some two weeks ago, and have noticed a positive effect on my mood (I dont suffer from any kind of mood disorder, i’ve just otices a more consistently good mood and increased emotional resilience). Due to gastrointestinal (apparently bacterial) symptoms I have not been able to consistently follow your advice on incorporating starches into my diet, so dietary changes can’t account for the change. I’m wondering if IFing has some direct effect on neurotransmitters or whether the effect I’m noticing might have something to do with a fasting-related decrease in a potential intra-cellular infection or something along those lines.


  43. Hi Lilian,

    A great many people have reported mood improvements on our diet, with or without IF, but I am not sure what the mechanism is. There are probably multiple mechanisms. I actually have started notes for a blog post on that, but I have no firm conclusions.

    If dietary changes were not responsible, then I would guess ketosis was probably the most likely cause in your case. You might try adding a bit of coconut oil to your diet and see if that helps also.

    Best, Paul

  44. Thank you, Paul.
    This is admittedly based on a very subjective observation, but I’m wondering if some kind of bacterial toxin could be one of those mechanisms. When I’m more symptomatic (extreme abdominal bloating) it seems to induce a mental/emotional state with some degree of malaise and mild agitation/irritation (indipendent of my direct emotioanal reaction being bloated). When fasting for 16-17 hours, and even after the subsequent light lunch, the opposite is true, as described in my previous post. I don’t know to what extent the mood effects of gut infections may have have been studied, so this is just an observation. Or perhpas bacteria in the gut as well as elsewhere are simultaneously affected by the fasting-induced ketosis? Whatever the case may be, we definitely seem to be ruled by the little buggers to a much greater extent than we’ve imagined..
    With thanks,

  45. Hi Paul,

    I’m sorry, I don’t really have a question…just a comment. In being a new visitor here, I enjoyed this article (and all the info I’ve come across on the website). But I also wanted to say thank you for your willingness to take the time and respond to so many of the comments personally. I don’t see that often on many blogs I visit.

    I think this shows a genuine concern for people and a strong desire to help, and I think I can speak for many readers here and say we all really appreciate this effort!

    All the best,

  46. Hi everyone,

    I came across something unusual today which I think you may be interested in Paul. It’s related to your idea that your palate adjusts the taste of food based on current requirements.

    Anyway, earlier today I was in the gym and performing a high intensity weight training session. I recently discovered Lindt’s 85%, 90% and 99% dark chocolate, purchased some of each and have been eating them a lot, and I decided to take some 90% along with me for afterwards to eat post-workout. This chocolate has very low carbs, 5g of sugar per 100g I think it is, but is absolutely delicious.

    On a normal day, the difference between 85%, 90% and 99% are substantial to me; I really notice the difference even between 85 and 90. As I say, I have been eating these for around a week now and have gotten used to what each tastes like.

    When I started eating the 90% after the workout, it tasted flavourless and took ages to get ready to swallow. I felt maybe it was something to do with saliva because it just wouldn’t go ‘mushy’ so I knew it was ready to swallow, it just stayed dry. It tasted of nothing. As I say, I’ve eaten a lot of this recently and it’s delicious; but yet now it literally just tasted flavourless. So I found this very surprising, and when I got home, I decided to try some 85% to see if It was the same with that. And it was. It gave exactly the same taste.

    Not long afterwards I ate 2 eggs and they tasted normal to me. I’m wondering what you think of this?

  47. Hi Leighan,

    Interesting experience, but I don’t know what it means. I’ve never experienced a time when chocolate wasn’t delicious! Perhaps I should try chocolate after working out.

  48. Yeah, I found it weird to say the least. Give it a go and see if it happens to you!

  49. Hey there Paul,

    I’ve recently purchased your book and am currently mid-way through reading it, what a wealth of information, I really appreciate the scientific take you guys brought to the paleo field.

    I have a quick question:

    I am currently following a ketogenic-paleo type diet (carbs up to 50g). I have noticed that when I introduce some the better fats like organic butter and coconut oil, I start having seborrheic dermatitis like symptoms appearing between my eyebrows (dry, scaling skin). I also typically have a more cloudy/foggy mind and tend to have considerable memory loss. This also happens to me while I eat organic fatty meat cuts (lamb, beef etc). However, when I switch to leaner cuts of meat (non organic from the butcher) and supplement with fats like macadamia oil in particular, the seborrheic dermatitis tends to go away, my brain feels much sharper (almost like it’s been turned on/stimulated) and my memory quickly improves. I would extremely appreciate if you could help me with the following:

    1. Would increasing my carb intake as per PHD might have any positive contribution here?

    2. Would you have any idea what the problem here is? All the good types of fats seem to spark either a negative response or a detox-like response (though I’ve stayed on the ‘good fats’for 4-5 months and the symptoms persisted until I switched to the leaner meat and mac. oil and things quickly imporved).

    The time spent writing this wonderful book and contributing to the community is vastly appreciated.

    Thank you,


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