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Kurt G. Harris MD

PāNu means paleonutrition. The "paleo" here signifies "old" and not necessarily paleolithic. The PāNu approach to nutrition is grounded on clinical medicine and basic sciences disciplined by knowledge of evolutionary biology and paleoanthropology. The best evidence from multiple disciplines supports eating a pastoral (animal-based) diet rather than a grain-based agricultural one, while avoiding what I call the neolithic agents of disease - wheat, excess fructose and excess linoleic acid.

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« KILL THIS BILL | Main | Comment Moderation »

Reader Ben on why carbs deserve a presumption of guilt

I find it very reassuring when a reader articulates my postion for me better than I do.
Here is reader Ben responding to Greg, who I think could fairly be described as in the "you need to prove a high carb macronutrient ratio is bad" camp.

Your description of a healthy carb is "one that contains nutrients" (sic), a la Weston Price.

That does not mean carbs are nutritious, it means nutrients are nutritious. As it stands, there is no evidence that carbs have a uniquely healthful contribution to a diet, as Taubes and others have argued. If I understand the former's position, he would argue that the absence of copious amounts of sugar, refined gluten grains or white rice (and fructose, probably) are the reasons the Kitavans are not disease-ridden, at least on the surface. This doesn't mean, however, that their diet is optimal or that those 60% carbs are beneficial -- ONLY that they are tolerated to the extent that they don't cause obesity.

Your two theories, to these eyes, appear to only say that perhaps only some carbs cause disease and the corollary point is that maybe some don't. This is merely a negative distinction: it has yet to be proven that carbs are needed at all in the diet and most anthropological and bio-chemical evidence suggests otherwise. The question is not WHETHER OR NOT a person can (superficially) tolerate more carbs under certain ethnographically-described scenarios, but whether that very scenario actually serves as reasonable scientific evidence that such a diet (or a similarly-constructed diet) be recommended to outsiders. There must be a scientific foundation for a claim that a particular diet is advantageous and as there is no strong evidence that the addition of 60% starchy carbs is in itself healthful and is, at best, likely a superfluity in an otherwise healthy lifestyle, the Kitavans example shouldn't serve as justification that the addition of said carbs for the rest of us will have a nutritional benefit.

Lastly, you claim that our knowledge of human body is flawed and, thus, all suppositions derived from biochemical analysis are in danger of being flawed. This argument is a canard, as no science-of-nutrition discoveries can take place in vacuum. It appears you are suggesting that the best alternative is to observe and emulate. M. Eades has rigorously argued that epidemiology/observation has no relevance to causality, so what dimensions of the "native" lifestyle are best emulated? The lack of sugar and flour? The increased amount of starchy tubers? Living in a jungle? As most of Price's evidence reveals that "diseases of civilization" are perpetuated exclusively by certain carb heavy foods in the diet, and this evidence correlates with a vast ocean of other scientific research, I'll take the negative stance that carbs are guilty until proven innocent (or necessary!).

Very well put, Ben.

You have identified the problem with putting ethnology before medical science. It is the same problem with modern economics.  Not enough careful thinking before looking at the data. WAPF, with many of its positions, ignores very sophisticated medical knowledge accumulated since Price's time, in favor of ethnology. The same argument about how you cannot just study modern folks on the SAD applies to modern-era HG stragglers.

You should study both groups from within a theoretical framework informed by modern medical bioscience. The "we don't know anything about human biochemistry" is a self sulfilling prophecy when you are too tilted in the empirical direction. You must study it to learn it, or you will have ideas like the only problem with cigarettes is the "artificial" chemicals and not the perfectly natural ones that are poisonous!

Reader Comments (33)

I don't see what the debate here is over anymore. Are we all in agreement that the goal is not to eat low carb, but instead to eat nutrient-dense foods, and that this goal will lead one to reduce carbohydrate intake?

November 4, 2009 | Unregistered CommenterGreg


Sounds reasonable to me.

November 4, 2009 | Registered CommenterKurt G. Harris MD

I have always eaten as many carbs as I've wanted. I grew up having huge plates of pasta, meats and potatoes, cookies, pies, cakes, breads. My (Sicilian) family seldom drank any was an occasional treat. When I was little I ate almost no fruits....the closest I got to consuming fruit was Hawaiian Punch. When I was young I seldom had deep fried foods like french fries. I have always been skinny, slender...thin. I take a 20 min walk most days. I tend to move a bit faster than the average person. I occasionally lift a little weights for toning. I am 56 yrs old, 5'7" and 120 lbs. Most of what we eat is homemade. None of my 3 grown kids are overweight...all are probably at at ideal BMI or below...they all eat carbs, starchy and otherwise. Why?

I am trying to help my husband get down to a more ideal weight. For the first month we had lots more steak and lower carbs, increased his use of coconut oil and cut out most industrial oils and snacks which include those. He has gone from 182 down to 167lbs within the last month and a half. He is 60 yrs old and 5'8". I felt like I would waste away to nothing if I didn't eat more carbs (so I've made pasta a few times recently) and I am afraid that he will not be satisfied in the long run. I am not convinced that low carb is necessary....that it is more the fructose, and industrial oils, and junk foods, that people consume and being laid back and slow. Years ago, he lost weight working with a personal trainer, eating an Adkins like diet (egg white omelets, skinless boneless chicken breasts etc. unsatisfying foods....he quickly gained it all back after going back to eating 'normally'.

I am not convinced that low cards is necessary. Ultimately, I am looking for optimal health and prevention for both of us. (both my parents died of colon cancer) Neither of us are on any meds.

November 4, 2009 | Unregistered CommenterLucy

Well... it depends... There are good and bad carbohydrates. Sometimes nutritionists recommend good-carb diets, rather than low-fat diets. A good carbohydrate diet is the “Glycemic Impact Diet”. I have read on Project Weight Loss that it’s all about learning how to eat healthy by avoiding certain carbohydrates which are bad for your body. It may be difficult to follow by people which are accustomed to eat fruits as a dessert, instead of a snack, or drink fruit juice at a meal, instead of before it.

EDIT: This is spam but I am letting it stand. Invoking nutritionists will not get you much traction with most of my readers -KGH

November 4, 2009 | Unregistered CommenterAlecu


Hawaiian punch is way worse than fruit - it's pure sugar. Maybe that was your point.
I grant that for most people eliminating the wheat and fructose matters more than avoiding just starchy carbs

However, in a food abundant environment I believe the macro ratios count for reasons I have stated -

Carb rich foods are good for survivial (in the evolutionary sense) but are nutrient poor.

Eating more of them rather than less crowds out nutritionally superior food.

Impaired fasting ability is another downside to a more glucose based metabolism. I have never met anyone eating over 50% carbs at any BMI who could comfortably fast for 24 hrs. It is easy if you are VLC or ZC.

It may interest you to know that colon cancer specifically has been linked to carb consumption.

November 4, 2009 | Registered CommenterKurt G. Harris MD

I think primitive people have no diseases of civilization because they don't have to drive to work and don't have to sit motionless all day long. They are also quite exposed to nature and fresh air, which have positive effects on emotional poise ( as compared to managerial pressure in sedendary office job ).

I feel distinctly better physically when between jobs. I move around, I do some fishing and body weight strength training, tendons permitting. The moment I get a job, however, I experience this:

Cessation of daily wheel running differentially alters fat oxidation capacity in liver, muscle, and adipose tissue.

On the topic of tendon inflammation, Kurt, do you think diet ( wheat, dairy, sugar, etc. ) and ascorbate status play a role ? Interesting that I only started to experience tendon inflammation when switching to super-slow or one-arm versions of body weight exercises.

November 4, 2009 | Unregistered CommenterIlya

Kurt, what specific positions of WAPF do you disagree with? Jermy


Not that many -You could do worse than to follow most of their advice. The only one that I'll mention for now is their stance on celiac disease and re-introducing gluten grains after you have healed from it. This advice could help you get cancer and autoimmune diseases, among other things.

I don't want to run a blog deconstructing other approaches. If you have a specific question about something you read there, I'll tell you what I think

November 4, 2009 | Unregistered CommenterJeremy


Given this understanding of carbs and nutrients, then we have no need to just dismiss the Kitavans or other cultures with a high carbohydrate intake and low levels of diseases.- instead we can work them into our theory. It is possible to be healthy (not necessarily *optimally* healthy) on a high carbohydrate diet if carbs are consumed them form a healthy source, given that the rest of the diet is extremely healthy, and one is reaping the other health benefits of living in an indigenous culture.

To a certain extent you have already stated this, but using language like the Kitavans "tolerated" carbs, and comparing it to smoking, which in my mind implies that carbs themselves are actively damaging, just as smoking is actively damaging. But we agree that (in the general case) it is not that carbs actively causing damage, it is the associated nutrient deficiency, and I think it is important to be clear on that distinction, along with the distinction of differing consequences depending on which types of carbs are consumed.

I think these distinctions do have practical implications- for Lucy it would make sense to advise that if she is going to continue to eat carb rich foods, she could likely improve her health by eliminating/reducing pasta and eating some type of potato in is place.

KGH responds:

Greg, I totally agree with everything you just said. Carbs are damaging to the extent they displace more desirable food. That is the sense in which I say most carb sources are "empty"

The only remaining point of contention might be that in addition to the displacement of other (animal based) foods, plant carb sources move our metabolism away from relying more on fatty acids and ketones. As I have said, I am less certain this is an advantage, but I think it might be, particularly as regards insulin and cancer. It seems highly unlikely the AUC for insulin can be optimally low on a 60% carbs diet. Again, that is from what I know about metabolism, and cannot be gleaned from ethnology, no matter how important or interesting that is.

BTW, when I say I am bored with the Kitavans, I am not dismissing them as people or as research material - I have read all of Lindeberg's papers and I take them seriously - I am saying their tolerance for carbs does not teach us that a higher carb fraction is in any way desirable. I am actually saying they fit my theory just fine, because we don't yet know as much as some seem to think we do about them, and because the carb ratio is not the sole and probably not even the most important parameter.

November 4, 2009 | Unregistered CommenterGreg

Of course, I would never drink crap like Hawaiian Punch was the point that when I did drink it as a child it didn't make me fat...nor did lots of pasta. Now we eat mostly whole, unprocessed or no refined foods. I've been reading WAPF stuff for the last few years. I make our own sourdough bread with about 1/2 fresh ground rye which lasts along time...we freeze it and maybe have a slice a day or less. But I also make sourdough pizza a few times a month too. I have a problem willingly giving up totally on I suppose I am a bit starchy carb addicted. It never made me fat but I don't want it to kill me either. When I have steak, I tend to enjoy a white or sweet potato filled with butter and maybe some sour cream and a salad...maybe arugula with lemon, olive oil, and a few shavings of Parmesan cheese . We have raw cream, milk, and butter. I mainly drink water, and a cup of red roibos tea with cream in the morning. My husband has bacon and eggs in the morning and I have bacon and maybe one egg yolk in a little cup of milk with vanilla in it.

The colon cancer/carb connection is of concern to me though. I used to be convinced it was the carcinogens in the charcoal bbq'd steak (lots of times with black char on them) my father made once every week and not the pasta that contributed to their getting colon cancer. His brother and a nephew both had colostomies. We had pasta a few times a week when I was growing up. But we also had only white bread for our well as SF french or sourdough bread(I grew up near SF). My father made his own sausages, sundried tomato paste, wine, olives, shot robins for the spaghetti sauce if I made the mistake of pointing out a pretty one. He loved his fruits and grew lots....he was skilled at grafting trees with several different different types of fruit on one tree. Maybe the high fruit consumption contributed....maybe it was the combination of various things along with a genetic propensity...but my mom died of it too at 52, my dad at 86. I rejected all fruits probably because he tried to push them on me and I didn't like the texture or taste. Now I can drink fruit smoothies with berries and cantaloupe...for the anti-inflammatory properties I think they provide,and I like enjoy baked apple occasional banana. We live in FL. I have regular colonoscopies and take supplements that have been found helpful in colon cancer prevention....and I understand the importance of a healthy diet. I avoid refined sugar for the most part. I still need more convincing that giving up all wheat and starches will help prevent colon cancer.

I tend to naturally intermittently fast....I don't usually feel the need to go 24 hours...but I have in the past. 12+ is no problem. I can eat a lot or a little....if I don't eat enough I get prone to constipation. My metabolism and my husbands seem to be completely opposite. He requires a nap every afternoon....and he needs his cup of coffee first thing in the morning and won't give it up. I can't tolerate caffeine....I am naturally more energetic.

I am just trying to figure this all out...I'll keep reading you and the rest of the low carb, paleo, primal, whole health source blogs..I also read Matt Stone's 180 blog...who isn't into low carbs. I am interested in permanent weight loss for my husband as well as the health aspects of trying to eat 'right'...if I can figure that out. He can't be bothered to read anything health/weight related...and left to himself he wouldn't have bothered losing the weight he's lost. I don't find weight around the middle at all attractive or healthy.

I am afraid I would waste away to nothing on VLC or ZC....I am not sure I could stomach the quantities of meats, eggs, cream etc. that I'd have to consume. Do you have what your typical diet actually consists of somewhere on this blog, Kurt? Sorry my comments have been so long.

KGH responds:

Hi Lucy

First, it is good to understand that BMI or body fat in no way guarantees you do not have metabolic syndrome. In fact, fat cells being more resistant to insulin relative to the rest of your tissue, can lead to thin folks getting diabetes. I weighed 169 at 5, 11"' when I was at about 50% carbs. You cannot rely on not being fat to indicate health.

I plan to post more about actual food I eat soon. In the meantime, try Freetheanimal. Richard's food porn and recipes are superb.

Thanks for your comments

November 4, 2009 | Unregistered CommenterLucy

Thanks for responding.

I've been reading Richards Free the Animal site and have tried a couple of his recipes...most recently his cauliflower almond side dish which was excellent.

I believe I am healthy and have never tested positive for diabetes or been prone to that....and that is certainly nothing I ever want to get. I haven't had a cold or flu for years....knock on wood. I know that being thin doesn't guarantee health...and good health is important to me. It just seems like most of the people who have gone VLC or LC were once obese or overweight. I am just trying to put it all together and understand it better. My father's parents lived to 97 and 93...he sister's were 93 and 103 when they died. They ate mostly homemade foods. They didn't get colon cancer. One of his sister's sons did get it. I'd love to know how much was diet related or gene related.

Last night's dinner: lamb chops, the cauliflower almond side, and an arugula salad.

November 4, 2009 | Unregistered CommenterLucy

A few questions for you Kurt:

What do you think is the significance of excess carbs being converted to saturated fat?

How does galactose as a carb compare to glucose and fructose?

(not trying to badger you, just curious about your view :)

November 4, 2009 | Unregistered CommenterDexter

For me, I think the interesting question is why the tolerance? Many people are unlikely to follow a ketogenic or nearly ketogenic diet. There are all sorts of reasons why, whether it's concerns for sustainability, or values, or whatever. So figuring out why is pretty important IMO if for no other reason than the larger public health question.

Me, I find the wheat/fructose theories both you and Stephen Guyenot writing about very compelling, and I also wonder about the usefulness of presumably very high levels of vitamin D given their sun exposure.

November 4, 2009 | Unregistered CommenterBeth

Ilya wrote:

"Interesting that I only started to experience tendon inflammation when switching to super-slow or one-arm versions of body weight exercises."

Hi Ilya,

I have been doing super-slow weight lifting for two years now as I have osteoporosis (and diabetes) - super-slow was originally developed (by Ken Hutchins) to help women with osteoporosis as it is very safe and effective at building muscle and increasing bone density. Serious weight trainers, like Frederick Hahn and Dr Doug McGuff also use super-slow as it is so effective at building muscle and strength. I too have experienced sore tendons in my hands and right elbow more recently. This happened as I moved on to much higher weights, it's as though my tendons cannot keep up with my improved muscle strength. I find that it is now helping to wear some hand protectors and an 'epi strap' on my arm.


November 4, 2009 | Unregistered CommenterAnne


I find your skepticism for the Kitavan model refreshing. And I agree, ethnography, while at times edifying, should not take the place of reason, rational thought and logic.


With regard to the Kitavans, why is the 800 lb gorilla in the room being ignored? Namely, the gorilla named Gene.

The Kitavans could be genetically adapted* to eating higher carb ratios than most of the people involved in the Paleo "movement" i.e. Caucasian Europeans.

What this suggests, if true, is that there may by not insignificant differences in optimal nutrition/diet between races -- and what is optimal for one race, may not be optimal for another.

*NB: I am not saying they are genetically adapted as such, I don't know if they are (no one does), but I am saying it is well within the realm of possibility given the differences between races.

For example (and shooting totally from the hip) -- I would guess given African-Americans' skin color, they are, on average, probably not getting enough daily sunlight and probably have need for more sunlight than European-Americans do. This may explain, in part, the rickets observed amongst African-Americans children.


Interesting thoughts.

I believe the fundamental aspects of macronutrient effect on metabolism are too invariant for there to be more than a moderate genetic component to the tolerance for carbs. The difference between human and chimp hemoglobin is like, one amino acid in 7 million years of divergence.

Of course, we know that some ethnic groups respond more poorly to the SAD than others, like the PIMA and other native american groups. I am just saying there cannot be enough variation to account for the suitability of carbs on a "metabolic typing" basis = the idea that some groups do better with carbs vis a vis fat, for instance.

November 4, 2009 | Unregistered CommenterPatrik

Kurt, once again, thank you for provocative blog posts that allow for such good debate. I've been waiting for the time to respond to your blog on the Kitavans.

In short, there really isn't a defense to what you have said about the Kitavans -- the burden of proof really is on the high carb diets to show that they are healthy. I have some ideas to share that show that the battle isn't really over yet.

First off, what do we know about species that are long lived? They have less polyunsaturated fat in their membranes, and more saturated/monounsaturated fats. (naked mole rat)

Here is some info on Kitavans:

If you look down on that page -- there is a telling statement The relations of palmitic acid to serum lipids may be explained in terms of endogenous fat synthesis at a low-fat intake, rather than reflecting its relative intake.

So, we know that if you keep polyunsaturated fat intake low, and total fat low, your body really only makes palmitic acid and keeps the ratio of palmitic acid to polynsaturates high <----- a good thing. So, at the very least, we know that the Kitavans have a membrance composition that is conducive to longevity. We know that eating monounsaturates or saturates doesn't really change membrance composition much (just do a search on Stephans' blog and you will find this) -- but that eating polyunsaturates alters membrance composition alot. So at least in the membrane department, the Kitavans are doing well.

I also assume that a high fat low carb diet could do the same thing -- but it always seems harder to avoid consuming polyunsaturated fats when you eat foods like eat foods like eggs (arachidonic acid) -- or pork fat, or typical omega 6 fed meats etc. you'd have to be carefully on a high fat diet -- however, it can be done.

Next, I'd like to point out that there just was an interesting study that came out on how excess fat causes inflammation:

Any diet that allows an individual to have a low BMI will benefit from less inflammation. Resultant excess fat from a high carb diet may be the only thing that makes it detrimental -- eat less or maintain a lower BMI (even if higher carb) -- like the Kitavans -- you may not see the excess inflammation or damage. I mentioned earlier that it is hard to change membrane composition when consuming saturated or monounsaturated fats. So, why not just consume a decent amount of monounsaturated fats to give your body less inflammatory signals than saturated fats (This will the argument of Micheal Rae <--- very well known figure in the caloric restriction world). Of course, saturated fats are usually never consumed in isolation -- and even a decent portion of heavy cream will convert, or is monounsaturated fat.

Here's another interesting tidbit on the naked mole rat:

The Mole rat endures much more oxidative stress -- yet lives longer! They live on a diet of tubers (carbs) and have very low insulin. Are we prepared to say that if we switched up a mole rats diet -- that they might live longer on a high fat diet? I've seen these kinds of arguments used by individuals like barry groves who say that gorillas would do better on a high fat diet -- I feel that the diet that gives the best longevity will be different than the diet that promotes the best possible health 'for the moment' -- The best diet for longevity will most likely deter the human body from "seeing" insulin (what I mean by this is that the growth factors that are the result of insulin-activity are turned down). Leading to low body mass, low muscle mass, and low growth parameters. Sounds a bit like caloric restriction to me. This happens on all diets if caloric intake is kept low.

We know that a high fat diet upregulates glutathione -- whether or not this turns up to be a positive is yet to be seen. Once again, it seems that increases in free radicals may be a good thing <---- jeez

Lastly, here's an interesting article by ray peat:

Personally, I've always noticed in increase in my cortisol and stress hormones when I've gone low carb -- whether or not that ends up being detrimental in the end <--- I'm not sure.

The most interesting thing I read from the article though was that there may be protective benefits from carb oxidation ( in that carbon dioxide may protect out cells) -- very low carb diets really ramp up oxygen usage <--- I hope this isn't a negative.

It's also interesting that he points out that insulin like activity is what matters most to the body-- and not absolute levels of insulin -- If you stay thin (think BMI 18,19), and keep your muscle mass lower, your expression of insulin and IGF-1 will be less. That will lead to greater longevity -- just like the caloric restriction studies in primates.

IGF-1 may be great if you want to promote growth or muscle mass -- but not so good for longevity though. This is the trade off of growth and power vs longevity.

As long as you eat a diet that covers the basics for the nutrients a human needs, and keep a relative low BMI -- your insulin signing will be low -- and you will live longer. And this is the case whether you eat a higher carb diet or lower carb one.

However, I will agree that it is easier to maintain a lower BMI on lower carb, and that is the way to go for those with damaged metabolisms without question.

PS -- I'm surprised you are still kinda suspect of veggies and or plant compounds -- there is so much good info at nephropal about how those certain compounds activate adiponectin and other beneficial processes in the body that it just seems like we do better when we consume them <--- even if they aren't magic!

November 5, 2009 | Unregistered CommenterAaron

I can comfortably fast for 24 hours on 50+% carbohydrate *if* I've eaten enough. Lately my thing has been to eat relatively high carb up until 2 hours before my evening hockey game(s) and then fast until dinner time the next day...depending on the timing of the game(s) that will be 20-24 hours. If I haven't eaten enough to make it through the fast, chances are I also haven't eaten enough to make it through the game without hunger or discomfort. I should note, though, that I do naturally carb-cycle to some extent and I don't know if that makes it easier to fast vs. consistent high-carb eating. I also don't have that "I never want to eat again" feeling you get on VLC, but that's fine.
I do think I have pretty good insulin function, and I also spend a good bit of my time with hungry skeletal muscle, so YMMV.

I lean towards the interpretation that fructose and sheer quantity are the problem more than all carbohydrates, but regardless I have a clear understanding that I eat them because I prefer to skate as if I had eaten them (skating on a LC diet has a very frustrating "I know I have a top gear, but no way am I seeing it tonight" quality), not because I think they're in any way necessary to good health. It's another trade off of what might be best for what is fun that I'm comfortable making.

November 5, 2009 | Unregistered CommenterKim


Good lord that's a long post!

Maybe you could pick one thing you want me to comment on, if that is what you want.

I like nephropal but don't endorse every opinion there. I eat plants that taste good as condiments

November 5, 2009 | Registered CommenterKurt G. Harris MD

"by individuals like barry groves who say that gorillas would do better on a high fat diet --"

Aaron, you have misunderstood what Barry wrote. He didn't say gorillas would do better on a high fat diet, he pointed out that they actually do have a high fat diet because all the fibre in the vegetation they eat is converted into short-chain fatty acids by bacteria in the colon and then they absorb and use the fatty acids.


I agree - that is what Groves said about both gorillas and herbivores. You are either designed to eat your fatty acids or make them - if you are not a foregut fermenter like a cow or a significant hindgut fermenter like a gorilla, Groves is saying you were designed to eat your fatty acid fuel sources. I agree with Groves.

November 5, 2009 | Unregistered CommenterJacqueline

AARON SAID: I also assume that a high fat low carb diet could do the same thing -- but it always seems harder to avoid consuming polyunsaturated fats when you eat foods like eat foods like eggs (arachidonic acid) -- or pork fat, or typical omega 6 fed meats etc. you'd have to be carefully on a high fat diet -- however, it can be done.

Whats the difference between a diet high in polyunsaturateds and palmitic acid?

KGH Responds:

palmitic acid is saturated fat - the goood kind

November 5, 2009 | Unregistered Commentermallory

i would have to also think alot of adults and children now have compromised digestion from not being breastfed, not being breastfed long enough, or inadequate breastmilk from a mothers SAD diet.... and after that from years of eating refined sugars, vegetable oils, and bleached enriched wheat flour. Only thing you have left that you could digest well enough is animal fat and protein. Alot of people now days would not have robust enough digestion to take on alot of plant food/carbs as our main macronutrient.


KGH responds:

I agree breast feeding as long as possible is optimal for the D and K and healthy fats - not sure it relates to carb tolerance, though

November 5, 2009 | Unregistered Commentertroy

Jacqueline, I was just taking a shot at the fact that Barry wrote an article entitled, "Should all animals eat a high fat, low carb diet?" I understand that gorillas eat a high fat diet vis a vis the fact that they are hind gut fermenters. Most of the fat they consume would be short chain fatty acids like butyric acid. Those acids directly fuel the stomachs of gorillas and are mainly used right there (we have a brain that needs lots of energy, they have a gut that needs lots of energy). To then extrapolate that we do best on large amounts of "long chain fatty acids" is a bit of a step because even gorillas or other plant eating mammals do not get a lot of the "long chain fatty acids". To be fair to Barry, I'm going to give a link to his article. Overall, Barry has done a lot to educate people about nutritional science, even if I don't believe everything he writes.

Mallory, I'm not sure what kind of response you were giving me by quoting something I said and than basically cut and pasting somebodies response to somebody else. All I was saying is that when you eat a high fat diet, you have to be mindful of your polyunsaturated fat intake. I don't feel that saturated fat is good and the other fats are bad. You need particular fats in particular amounts. As of right now, you should eat a diet that maintains a low level of polyunsaturated fats in your tissues. At least if you agree with the data on long lived species.

Kurt, sorry for the long winded post. I could have a much better conversation on this face to face (faster, and less typing!!) -- maybe i'll see you in a Milwaukee coffee shop one day (not too far from my native Chicago)!

In all seriousness though, my post was bascially trying to say that I believe the best diet for longevity would be the one that minimizes growth factors. Most low carb diets do this to some degree by lowering insulin as a result of taking out carbs. However, most low carb diets also start to up protein levels which seems to be the macronutrient that could be the most damaging. I forget where I have the link on protein restriction and longevity.

What do all the longest lived peoples usually have in common -- they are short, don't have excess fat, and don't have lots of muscle mass. (LOW GROWTH FACTORS)

My question to you, even if insulin is kept low on a super low carb diet, how do we know the body is not compensating by increasing other growth factors (which we know it is, HGH, IGF-1). I see low carb people all the time that have great muscle mass, if growth factors are implicated in reducing longevity, how do we resolve the fact that the diet for the best possible health for the moment might be at odds for the best possible diet in terms of longevity?

When I look at a Kitavan -- they have a low BMI, no excessive muscle mass, and they are not that tall. They don't mess their livers with fructose, and they don't destroy their intestines with wheat.

It seems that if you maintain a low BMI, lower muscle mass, low growth factors (which might also be low protein). Non fructose carb consumption seems to do little to you. Now, if this might be totally different if you have already messed up your ability to process carbs: (look down to where it makes conjectures about insulin sensitive individuals)

I just want to hear someone say that carbs aren't the enemy, as long as you can maintain a low BMI, don't consume excess fructose, and consume most of the other vitamins and minerals you need to function.

In fact, as long as you keep your BMI down, a higher carb diet may be the one that it is easiest to maintain a high tissue concentration of saturated to polyunsaturated fat -- and the best way to keep growth factors down, "if" you can watch what you eat! <---- and you cannot overeat, or have excess fat. That is very hard on a high carb diet, but possible.

Most people cannot do the above, in that case, use a low carb diet to maintain a low BMI.

November 5, 2009 | Unregistered CommenterAaron

sorry, i just wanted to know what palmitic acid was... thats why i quoted you


nothing to apologize for

November 5, 2009 | Unregistered Commentermallory

Aaron, could you quantify your expected return on varying your macronutrient content to include carbs? What is your health goal, and what would you rate as success?

I think everyone here is interested in removing their risk of the standard diseases of civilization, but I'm not so sure that people are trying to maximize lifespan via macronutrient tweaking. Genetic luck appears to be a strong factor in that regard, and my cursory glance over the longevity debate left me thinking that everything was so far from converging on any useful advice that I might as well throw a dart.

November 5, 2009 | Unregistered Commenterpfw

pfw, I like how you have phrased your question! I am very privy to the fact that one who is trying to tweak everything for longevity will be different than someone who is really battling health problems.

If you are experiencing health problems, are overweight, and have problems with your blood sugar and insulin -- cut carbs down -- right away -- this goes for anyone! Almost all studies show the superiority of lower carb diets when your tissues are shown to be insulin resistant. This doesn't mean cut carbs to 0 though.

Once you've gotten your blood sugar and insulin down -- and have a low BMI, the picture changes somewhat -- I'd argue it's rare to see individuals with blood sugar issues who have a BMI around 18,19 <--- even if they consume carbs.

My health goal is to live as healthy as possible without going crazy in restricting any type of food. I don't want to relegate food to the realm of fuel only, and I really enjoy different types of flavors. I find that if I restrict carbs, my protein intake creeps up to the point where I feel that I get slight allergenic symptoms from major protein foods -- like eggs, red meat, fowl, dairy. These symptoms could be a slight scratchy throat, increased mucus and so on. I seem to get hypervigilant, and have problems relaxing (probably due to increases in cortisol). Too much fat in general just does not make me feel that great -- even after weeks of trying to adapt. <---- remember, this is me, not you. Adding carb foods calms me down-- and that is important for 'ME'.

For example, I ate chicken wings with homemade sweet potato fries for lunch. And for dinner, I had a large salad with grass fed beef and a can of sweet corn as my dessert. I was at work and couldn't prepare my meal at home. I don't like to deny myself anything if I really want it -- life is too short.

Lastly, I do utilize foods like buckwheat, rice, potatoes because they just don't give me the same slight allergenic symptoms that eggs, meat, chicken, and dairy do. If someone does not have my problems -- or feel like they are on stimulants when on a high fat diet -- feel free to eat fat!

November 5, 2009 | Unregistered CommenterAaron

amen to this post and the one about Kitavans

November 5, 2009 | Unregistered CommenterAthanasios

Mallory, sorry, I didn't know Dr Harris's comments can go right under your post!! That's why there was weird confusion on my part for how you asked a question.

November 5, 2009 | Unregistered CommenterAaron


I already link to and recommend nephropal, no need to keep linking it.

We know you believe in STP.

However, I spend a lot of time fighting the concept of magic foods.

Feel free to start your own Durk and Sandy Pearson blog . I promise I'll come and visit!

November 5, 2009 | Registered CommenterKurt G. Harris MD

"We know you believe in STP."

Kurt, isn't STP a motor racing oil?


STP was a "magic" engine additive that everyone thought was great when I was a kid - it did absolutely nothing for engine performance

November 6, 2009 | Unregistered Commenterj

"My health goal is to live as healthy as possible without going crazy in restricting any type of food. I don't want to relegate food to the realm of fuel only, and I really enjoy different types of flavors. I find that if I restrict carbs, my protein intake creeps up to the point where I feel that I get slight allergenic symptoms from major protein foods -- like eggs, red meat, fowl, dairy. These symptoms could be a slight scratchy throat, increased mucus and so on. I seem to get hypervigilant, and have problems relaxing (probably due to increases in cortisol). Too much fat in general just does not make me feel that great -- even after weeks of trying to adapt. <---- remember, this is me, not you. Adding carb foods calms me down-- and that is important for 'ME'."

do you have reasoning for this?i always wonder how allergies appear that didnt previously exist when one is on a VLC diet

November 6, 2009 | Unregistered Commentermallory


I'm not so sure low BMI = good health. I remained thin eating loads of carbs- felt fine, no signs of disease. Then at 38 I was diagnosed with cancer (no family history, genetic tesing showed nothing). I wonder if it was all the carbs...

November 7, 2009 | Unregistered Commentersandra

Mallory, It's possible allergies occur because of a higher protein content -- I usually never have mucus type symptoms with carb foods -- but then again - i have felt lectin-esc problems in my knees from certain carb foods <--- whether or not this is just due to carbs or the lectins in the foods, I'm not sure

The type of diet Dr. Harris lays out is good because he doesn't stress protein- and reminds people to fast and watch meal frequency <---- which I think it a large contributor to allergenic-like symptoms

Sandra, I am so sorry about your condition (I HOPE IT IS A PAST CONDITION!!!). Cancer is such a nasty disease, I hope we wipe it out in my lifetime!

Choosing a diet to fight cancer is much different than trying to optimize for longevity.

Personally, If I had cancer, I'd severly restrict glucose, I'd try to reduce growth-like factors (insulin, IGF1) in my body by dietary manipulation, I'd use plant like compounds that encourage cancer cells to commit suicide (ketogenic diet encourages this also), try to stay as active as I could to maintain muscle mass and #1:

Consult a physician to explain to me options I may have not even known about!

Low BMI isn't really a good thing when you are ill -- you draw upon your muscle reserve in those conditions -- otherwise, it is good to have a low BMI because excess fat can be inflammatory.

Personally I don't believe a low fat diet causes cancer -- and after I saw the latest study on worms -- I believe that more. Only a diet that was loaded with fat and carbs was truly nasty. However, I feel like I could of improved on the low fat diet (in terms of less fructose, more monunsaturates<--- which have pretty neutral effects on insulin vs saturated fat). And, it would have been harder to improve the ketogenic diet, because by nature, it was already 0 carbs.

And I'll stand by my claim 100% that a diet that creates the lowest levels in insulin activity, IGF-1, and growth factors (which includes HGH) while maintaining low levels of polyunsaturated fats in membranes will lead to the best longevity possible.

Does anyone disagree with that?


Aaron, I am not sure what you mean by "stand by your claim" surely you admit this claim is informed speculation - nothing wrong wiht that but it is not proven.

If I were diagnosed with cancer I would get on a ketogenic diet immediately. As much as 85% fat, 15% protein or maybe 80/10/5. Get Vitamin D levels above 100 ng/dl - no proof that is better but insurance against lab miscalibration.

November 7, 2009 | Unregistered CommenterAaron

AARON: Kurt, you are correct, all I have is big picture speculations. I know better than to to use an affirmation statement like I did.

Honestly, I got to my current position by asking myself what characteristics in a person leads to longevity or health. Most of the time, the research shows benefits to low growth, low insulin, low IGF-1, delayed reproduction, and lower than normal thyroxine. Some research even shows some longevity benefits to being slightly insulin resistant.

An interesting aside though, its good to promote IGF-1 though when you are sick or need to increase muscle mass. Human bodies seem to mandate a need to switch between growth and repair and not stay too much in one of the categories. People seem to get pigeon holed into one diet or anther. I constantly vary my macronutrients depending on what i want to accomplish.

KGH COMMENTS: My paradigm assumes diet it parametric. Within parameters that mimic the EM2, it makes most sense to me our bodies should be competent to decide when to switch to the growth and repair promoting mode.

AARON AGAIN: I think it is a good thing to fast and go without eating (or at least cut down meal frequency to 2 meals or less a day). That allows my body to rest from digestion and switches on repair mechanisms. Once food is reintroduced however, I ask myself, do I really want to stay in the ketogenic state where my body is primarily burning fat? I find that my body is much less stressed when I allow it to have some carbs at that stage to fill my glycogen reserves and allow serotonin to relax me. As long as I don't overeat and keep my BMI low, my biomarkers will stay good.

KGH RESPONDS: See the latest post.

November 8, 2009 | Unregistered Commenterhalotek

Hi Dr Harris

Wondering if you've seen and would care to comment on this study comparing effects of a ketogenic low carb diet vs a non-ketogenic low carb diet.

I'm particularly interested in knowing what you think about the different effects the two diets had on "inflammatory risk" (arachidonic acid:eicosapentaenoic acid ratio) and the higher LDL levels found in the ketogenic dieters.

November 14, 2009 | Unregistered CommenterMickey
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