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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« Primal Blueprint | Main | Insulin is a doorman at the fat cell nightclub, not a lock on the door »

Where are the fat carnivores?

Well if you are going to point out "holes" in my blog posts, you will risk becoming fodder for new posts.

Most people seem to get it. Some don't. This is for them. The rest of you can skip it.

Today I am asked"

If it was possible to grow fat by eating only meat, or eating only a boatload of animal fat, then where are the fat carnivores?

We do agree that by "grow fat", we mean "grow obese" like a hippopotamus would or a gorilla would or a human would if he ate carbs. Otherwise, it's a good logical refutable solid valid hypothesis you have there.

My response is:

What hypothesis? I have seen and read plenty of testimony from people who have gained weight eating nothing but fat and protein. It's not a "hypothesis" and it is not mysterious or surprising. It only mystifies me that people consider this controversial or even interesting, really.

As far as my definitions, when I say store fat, I mean exactly that. Store fat in a fat cell. I do not mean "get clinically obese".

I do not dispute that it is harder to get obese on VLC. That is obvious. But if you have disturbed leptin signaling or otherwise screwed up body fat setpoint, you could become obese or stay obese (we see this all the time!) on VLC or ZC.

So Here we go, one more time:

It is easier to store fat by eating carbohydrate than by eating fat. Insulin has something to do with this. We all know this, and no one is disputing it.

However, this does not mean you cannot store fat without eating carbohydrate. (Don't confuse EATING carbohydrate with having it available in your body) I just got done explaining that fat is being stored and released simultaneously ALL THE TIME. If you could not have net fat storage with no carbs IN YOUR DIET, then every time you fasted on zero carbs, you would lose fat, and when you next ate you would not store any.

Guess what would happen then? You would eventually go to 0% body fat. Have you met a zero carber with no body fat? Maybe you can show me one subject. I'll publish it as a case report and give you some credit.

Same thing with wild carnivores that eat no carbohydrate. If you can show me one with no body fat, then that animal might not be storing fat. Any animal that has fat is by definition storing it. And if they don't have periods with net positive fat storage, they would DIE due to the cumulative losses of adipose as they burn fat in between eating. 

A bucket that has a leak in it that has no way to fill it is by definition always empty - it has to be.

Next fallacy:

Wild animals and wild humans that are not obese are not obese because they are not damaged. It has exactly zero to do with whether their diet normally has carbohydrate in it.

Animals that have more stored body fat, like hippos, are not obese either. They are animals that have more body fat and are evolved to. Carnivores don't have lots of stored adipose because, I don't know, have you ever tried to chase a gazelle while carrying 100 lbs of stored fat? Obesity is "more fat than you are supposed to have", not "more fat than a human". Don't be anthropocentric.

Now read those 4 paragraphs I just wrote several times, and forget all the nonsense you heard from "The Bear" or whomever.

Reader Comments (22)

Hey, how come the bear doesn't eat a bunch of acorns and berries to store up fat for the winter? More importantly, why does he call himself "The Bear" if he eats an all-meat diet? This could be the dumbest thing since people started plowing through giant plates of barbecue chicken and cornbread while announcing, "I eat like a horse!" I vote that "The Bear" change his name to "The Tiger." I think chicks would dig that more anyway.

March 17, 2010 | Unregistered CommenterMatt Stone

Thank you for this....learning so much every day from your blog and user comments. So I am wondering, is there any way to test if you have disturbed leptin signaling or otherwise screwed up body fat setpoint? What about hypothalamus/pituitary testing? Testing for a bowel obstruction? Something ain't right with my body and I am trying to figure out what it might be. Doctors are not of much help - unfortunately. No disrespect to you Dr. Harris.

March 17, 2010 | Unregistered CommenterKristina

Dr. Harris,

I like the idea of fat being stored and retrieved on a regular overlapping basis, back and forth; and, muscle tissue broken down and repaired, too, liberating its constituents even in the absence of any dietary glucose deficiencies. It sounds a lot like good housekeeping to me.

Hmm? Since fat soluble vitamins are stored in fat until needed, could this account for the need for fat burning on a regular basis? If the particular fat in a diet, at any given time, lacks a particular vitamin, wouldn't the body need to acquire it from storage fat? I suppose there are other reasons for a tandem fat store/burn cycle, but liberating vitamins could be a factor.


Cheers! Brad

KGH: Release of fat would not be required for fat soluble vitamins to equilibrate, IMO.

March 17, 2010 | Unregistered CommenterBrad Reid

If the human race couldn't get fat from eating fat then I guess we wouldn't be here?

KGH: Obesity is a phenomenon of body fat set-point, not caused by accidently eating too much fat.

March 17, 2010 | Unregistered CommenterWinalot

Dr. Harris, thanks so much for all the work you put into this blog. I've been reading it over and over, trying to wrap my head around all the concepts and research you discuss. With so much contradictory medical/nutritional/science info out there, I really appreciate having a resource that I feel like I can trust.

In that vein, would you please elaborate a bit about set point? I thought that was a myth.

Thanks again.

KGH: WHy would you think that? If you do not weight or measure, there has to be a set point.

March 17, 2010 | Unregistered CommenterAlicia

Any man on a low carb whole foods diet who has no metabolic disorder deserves a medal if he can eat so much to become obese. I would vomit. As a low carb adult male 6.0ft 165 lbs who benches 315 I go through periods of eating as few as 1000 calories a day because I feel too full.

March 17, 2010 | Unregistered Commenterzach

I've often wondered about the availability of high sugar foods during
paleolithic times. These were only available for a releativly short time
period in late summer/early autumn.

Could it be that humans ate the fruits of autumn to store fat for the
coming winter when food would be scarce? Even vegetables were
not around for the entire year.


March 17, 2010 | Unregistered CommenterScott Hamilton

Gorillas aren't obese. A 700-lb male gorilla has something like 3% bodyfat. Their shape is due to the large gut required to process plant material. I don't know about hippos, but I'll bet it's a similar deal.

Bears (or at least grizzly bears) get fat for the winter mostly by eating grass. Interestingly, once the reach a certain age, the lose the ability to store fat no matter how much they eat, and basically starve to death over the winter. Another great example of how fat storage is driven primarily by hormones.

KGH: Correct about gorillas. Primates get obese on chow and ad-lid fruit in the zoo. My point was to not define obesity anthropometrically.

March 17, 2010 | Unregistered CommenterDave

<Primates get obese on chow and ad-lid fruit in the zoo. >

They seem to get diabetes too. Perth zoo (in Australia) has a lot of diabetic orang-utans. I've always wondered how they could have become diabetic - been meaning to ask Peter - but perhaps it's just that they're given more fruit (or year-round fruit) and not enough leaves or whatever else it is they eat in the jungles.

KGH: One of the ways the toxicity of fructose is naturally regulated is the amount of work in procuring and eating wild fruit.. this is pretty attenuated in the zoo with bags of sugar.

March 17, 2010 | Unregistered CommenterJacqueline

WOW! My friend just sent me a link to one of your posts. Incredible.

This is one of the single best blogs I have ever come across on health, nutrition and such.

Keep up the excellent work.

You NEED to put out a book. There are lots of time efficient ways to do that - you can have someone interview you and get someone else to transcribe and edit it, and then have someone else do fact checking. (Most of that could be done for free or very low cost with interns. There are probably a lot of people who would be interested in doing the grunt work for you just to learn from you.)



Thanks, Josef. I plan to use speech recognition on my mac. Hiring out compilation of references and fact-checking is a good idea.

March 17, 2010 | Unregistered CommenterJosef Brandenburg

One thing I haven't seen low-carb proponents mention is the apparent fact that once fat cells are made they never die and can only shrink to a certain size. Perhaps this could be one of the reasons that the body will settle at a certain point and that weight cannot be safely dropped below a certain level without inducing hunger, amongst many other metabolic issues. I have looked at numerous zc/vlc journals and the vast majority of 40+ individuals seem to lose weight until a point and stall. But maybe there is hope for those struggling to lose when they eat this way for several years as there is sparse data or journaling for indefinite journeys on zc/lc.

As for 'the bear', who got his nickname for being very hairy - although he was unrelenting of some of his clearly wrong ideas on dietary fat storage, he did get more right than wrong and had a profound impact on moving lots of people towards vlc, which he should be given some credit for.

March 17, 2010 | Unregistered CommenterTeddy

re fat carnivores: maybe (farm-raised) alligators?


Who knew?

KGH: Interesting, thanks. A gentle suggestion - use the tiny url program for these long ones.

March 17, 2010 | Unregistered Commentercaphuff

Bear capping thread! Seriously, that dude deserves little credit, because he engages in sloppy thinking. He mentions scientific research in one post (of some papers that he can't seem to find and correctly cite, such as glycogen isn't used during exercise) in the next says he doesn't need scientific research to confirm his n=1 experience and thus support his argument. He trolled for disciples, and he got it at the Zerocarbers. They should call themselves Sheep for how they uncritically venerate him, and how they discourage dissent and argument. According to them, apparently you don't need much Vitamin D.

March 17, 2010 | Unregistered Commenterjclements

jclements: "...and how they discourage dissent and argument."

Yes nowadays the ZIOH forum looks more like a cult than a science-oriented health site. It's a shame.


March 17, 2010 | Unregistered CommenterPatrick N.

As someone without any scientific background, I really appreciate posts like these. I'm easily distracted by the siren song of overly simple, black and white, extreme views (like Zero Carbs). It's really valuable for me to see these claims laid out clearly and their faulty logic exposed, using what amounts to common sense. Great post.

March 17, 2010 | Unregistered CommenterEsoteric Fish

@Teddy: "I have looked at numerous zc/vlc journals and the vast majority of 40+ individuals seem to lose weight until a point and stall."

I suspect that a large percentage of low-carbers continue to ingest a significant amount of PUFA, in the form of mayo, salad dressings, olive oil, and so on. These would continue to aggravate NAFLD and broken metabolism.

The Eades address this issue in their recent book, "The 6-Week Cure For the Middle-Aged Middle." Indeed, some low-carbers (not zero carbers) continue to eat fruit, even if only in limited amounts. They make a number of suggestions that go beyond mere carb restriction. These include elimination of all vegetable oils, increased consumption of saturated fats, and use of leucine, either as a supplement or in protein powder. Whether these are the best suggestions is something that should be discussed. Those of us with "broken metabolisms" in fact have broken livers. For us, healing the liver is a priority. ZC may be an option (the Eades recommend a stint of ZC), but perhaps there are others. I've read that Betaine HCl supplementation is beneficial for people with NAFLD. In short, those who need to reverse liver damage may need to take steps beyond those required of people who are trying to prevent it.


The liver has amazing regenerative capacity, more than any other solid organ. Just giving it a good long rest and not insulting it is the main thing.

I agree that many low carbers are indifferent to consuming large amounts of PUFA (TYP approach is one example) in items such as mayonnaise, and the usual "healthy" oils and nut butters - which is worse than starches for sure. One reason mine is not really a "low carb" approach.

March 18, 2010 | Unregistered CommenterTodd

Maybe slightly off topic here, but still it has to do with insulin and fat storage:
I just read here: http://heartscanblog.blogspot.com/2010/03/atkins-diet-common-errors.html
that "Dairy products, especially milk, yogurt, cottage cheese, and butter, are potent insulinotropic foods, i.e., foods that trigger insulin release. There can be up to a tripling of insulin (area-under-the-curve) levels. This is not good in a world populated with tired, overworked pancreases, exhausted from a lifetime of high-carbohydrate eating."
Now that worries me a lot, since I eat a lot of butter and cream, Dr. Davis doesn´t mention the latter, but who knows.
Kurt, can you help us out?


I eat butter and cream every single day. None of the insulinogenic cheeses or milk (which I consume little of) is even close to the insulinogenic effect of a baked potato or chocolate chip cookies or pasta or bread.

Describing butter, which is more than 90% fat calorically, as insulinotropic is just nonsense.

Sometimes it's time to just pick sources you trust (I suggest the ones on my blogroll) and stick to them.

March 18, 2010 | Unregistered CommenterGeorge

@KGH re "The liver has amazing regenerative capacity, more than any other solid organ. Just giving it a good long rest and not insulting it is the main thing."

I think I'll have a large fridge magnetic sticker made that says "It's the liver, stupid."

March 18, 2010 | Unregistered CommenterTodd

George: "Dairy products, especially milk, yogurt, cottage cheese, and butter, are potent insulinotropic foods, i.e., foods that trigger insulin release."

Butter does not belong in that list, really !


March 18, 2010 | Unregistered CommenterPatrick N.

Regarding the question about set points, I don't know the answer, but I think the idea about set points being a myth is coming from Taubes / GCBC, chapter 24.

March 18, 2010 | Unregistered Commenteravocado

Here is my favorite quote from Taubes' GCBC book.

Pages 349 and 350.

"Pennington proposed that a metabolic defect is what causes obesity in humans. The adipose tissue amasses fat calories in a normal manner after meals, but it doesn’t release those calories fast enough, for whatever reason, to satisfy the needs of the cells between meals.

By hypothesizing the existence of such a defect, Pennington was able to explain the entire spectrum of observations about obesity in humans and animals simply by applying the same law of energy conservation that other obesity researchers had misinterpreted. The law applies to the fat tissue, Pennington noted, just as it does to the entire human body. If energy goes into the fat tissue faster than it comes out, the energy stored in the fat tissue has to increase. Any metabolic phenomenon that slows down the release of fat from the fat tissue—that retards the “energy out” variable of the equation—will have this effect, as long as the rate at which fat enters the adipose tissue (the energy in) remains unchanged, or at least does not decrease by an equal or greater amount. Fat calories accumulating in the adipose tissue wouldn’t be available to the cells for fuel. We would have to eat more to compensate, or expend less energy, or both. We’d be hungrier or more lethargic than individuals without such a defect.

Pennington suggested that as the adipose tissue accumulates fat its expansion will increase the rate at which fat calories are released back into the bloodstream (just as inflating a balloon will increase the air pressure inside the balloon and the rate at which air is expelled out of the balloon if the air is allowed to escape), and this could eventually compensate for the initial defect itself. We will continue to accumulate fat—and so continue to be in positive energy balance—until we reach a new equilibrium and the flow of fat calories out of the adipose tissue once again matches the flow of calories in. At this point, Pennington said, “the size of the adipose deposits, though larger than formerly, remains constant: the weight curve strikes a plateau, and the food intake is, again, balanced to the caloric output.”

By Pennington’s logic obesity is simply the body’s way of compensating for a defect in the storage and metabolism of fat. The compensation, he said, occurs homeostatically, without any conscious intervention. It works by a negative feedback loop. By expanding with fat, the adipose tissue “provides for a more effective release of fat for the energy needs of the body.” Meanwhile, the conditions at the cellular level remain constant; the cells and tissues continue to function normally, and they do so even if we have to become obese to make this happen.

This notion of obesity as a compensatory expansion of the fat tissue came as a revelation to Pennington: “It dawned on me with such clarity that I felt stupid for not having seen it before.” By working through the further consequences of this compensatory process, Pennington said, all the seemingly contradictory findings in the field suddenly fit together “like clockwork.”

This defect in fat metabolism would explain the sedentary behavior typically associated with obesity, and why all of us, fat and lean, will become easily fatigued when we restrict calories for any length of time. Rather than drawing on the fat stores for more energy, the body would compensate by expending less energy. Any attempt to create a negative energy balance, even by exercise, would be expected to have the same effect."

I like it very much because whatever the causes of this defect are, it still explains obesity. It is open-ended and future proof. As far as I know, this hypothesis is still valid.


March 18, 2010 | Unregistered CommenterPatrick N.

Kurt, from my understanding, black coffee stimulates insulin release. My question is, how much? I've never read anything credible on the subject. I assume it's only a tiny fraction as compared to drinking an equivalent amount of "orange juice" or some other sugary concoction, but that's little more than an assumption. Any thoughts or sources where I could find out more?



KGH: Big doses of caffeine can cause IR - like a whole pot of coffee a day, maybe. A cup or two a day if you are normal is probably OK.

March 18, 2010 | Unregistered CommenterAnthony
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