More Reasons to Eat Fat

Peter Turchin


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In a recent blog post P. D. Mangan discusses the implications of the metabolic theory of cancer and the ideas of Dr. Laurent Schwartz, French physician and oncologist, who has been using this theory to treat cancer patients. Whether this theory is correct, or not, time (and the scientific method) will tell. But there is one non-controversial observation that has huge implications for treatment–and prevention–of cancer.

As I explained in a previous post Food for Thought, our cells can utilize two main sources of energy: glucose, which is derived from the carbohydrates, and ketones, which are derived from fats. In many types of cancer, cancerous cells lose the ability to metabolize ketones, and are forced to rely solely on glucose. Thus, a simple lifestyle-based strategy to inhibit tumor growth is to switch to a ketogenic diet. In other words, drastically reducing carbohydrates and substituting them with saturated fats will not affect the function of muscle and brain cells, but will starve cancerous cells. In fact, a fat-based diet may also prevent cancer, because most of us have many tiny incipient tumors that are being constantly clobbered down by our immune systems. It’s only when they escape this constant policing action that they become a problem. Starving them of energy gives the immune system additional time to find and destroy them.

And this reminds me of the entry I submitted in response to the Edge question of 2016 a year ago:


The responses to this question, including mine, were recently published in a book form, and I think it’s worthwhile to revisit it again, in light of the new information on cancer treatment. It appears that the anti-fat craze not only made us fatter and more stupid, as I point out in this essay, but also more susceptible to dying from cancer.


Amid all the confusing fluctuations in dietary fashion to which Americans have been exposed since the 1960s, one recommendation has remained unchallenged. Beginning in the 1960s and until 2015 the Americans have been getting consistent dietary advice: fat, especially saturated fat, is bad for your health. By the 1980s, the belief equating a low-fat diet with better health had become enshrined in the national dietary advice from the US Department of Agriculture and was endorsed by the surgeon general. Meanwhile, as Americans ate less fat, they steadily became more obese.


Of course, the obesity epidemic probably has many causes, not all well understood. But it is becoming clear that the misguided dietary advice with which we have been bombarded over the past five decades, is an important contributing factor.


In fact, there has never been any scientific evidence that cutting down total fat consumption has any positive effect on health; specifically, reduced risks of heart disease and diabetes. For years those who pointed this out were marginalized, but recently evidence debunking the supposed benefits of low-fat diets has reached a critical mass, so that a mainstream magazine such as Time could write in 2014: “Scientists labeled fat the enemy. Why they were wrong.” And now the official Scientific Report of the 2015 Dietary Guidelines Advisory Committee admits that much.


There are several reasons why eating a low-fat diet is actually bad for your health. One is that if you lower the proportion of fat in your diet, you must replace it with something else. Eating more carbohydrates (whether refined or “complex”) increases your chances of becoming diabetic. Eating more proteins increases your chances of getting gout.

But perhaps a more important reason is that many Americans stopped eating food, and switched to highly-processed food substitutes: margarine, processed meats (such as the original Spam—not to be confused with email spam), low-fat cookies, and so on. In each case, we now have abundant evidence that these are “anti-health foods”, because they contain artificial trans fats, preservatives, or highly-processed carbohydrates.

While controlled diet studies are important and necessary for making informed decisions about our diets, an exciting recent scientific breakthrough has resulted from the infusion of evolutionary science into nutrition science. After all, you need first to figure out what hypotheses you want to test with controlled trials, and evolution turned out to be a fertile generator of theoretical ideas for such tests.

One of the sources of ideas to test clinically is the growing knowledge of the characteristic diets of early human beings. Consider this simple idea (although it clearly was too much for traditional nutritionists): we will be better adapted to something eaten by our ancestors over millions of years than to, say, margarine, which we first encountered only 100 years ago. Or take a food like wheat, to which some populations (those in the Fertile Crescent) have been exposed for 10,000 years, and others (Pacific Islanders) for only 200 years. Is it surprising that Pacific Islanders have the greatest prevalence of obesity in the world (higher even than in the United States)? And should we really tell them to switch to a Mediterranean diet, heavy on grains, pulses, and dairy, to which they’ve had no evolutionary exposure whatsoever?

Our knowledge of ancestral diets, of course, is itself evolving very rapidly. But it seems clear that we are adapted to eating a variety of fatty foods, including grass-fed ruminants (beef and lamb) and seafood (oily fish), both good sources of Omega-3 fatty acids. Of particular importance could be bone marrow—it is quite likely that first members of the genus Homo (e.g., habilis) were not hunters, but scavengers who competed with hyenas for large marrow bones. It’s very probable that nutrients from bone marrow (and brains!) of scavenged savannah ungulates were the key resource for the evolution of our own oversized brains.

In light of the new knowledge it is clear why Americans are getting fatter by eating low-fat diets. When you eliminate fatty foods that your body and—especially—brain need, your body will start sending you persistent signals that you are malnourished. So you will overeat on foods other than fatty ones. The extra, unnecessary calories that you consume (probably from carbohydrates) will be stored as fat. As a result, you will be unhappy, unhealthy, and overweight. You can avoid those extra pounds, of course, if you have a steely will (which few people have)—then you will not be overweight, merely unhappy and unhealthy.

So to lose fat you need to eat—not fat—but fatty foods. Paradoxically, eating enough fatty food of the right sorts will help to make you lean, as well as happy and—Edge readers, take note—smart!

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Peter Payne

Interesting, and I have encountered these ideas before. One question I always have is, I understand there is a well-established connection between meat consumption and cancer/heart disease? And where else than meat are you going to get a good dose of saturated fat? I’m genuinely interested in this.

Aaron Blaisdell

Here are a few excellent blog posts from bloggers I know very well and trust, discussing the red meat-cancer relationship (or, lack thereof) along with some sage advice as to how to interpret observational studies:


al loomis

need to see diet and health data on eskimos. but certainly worth looking at- they used to get little carbs in traditional diet, lots of fat. probably true of all h-g socieites.

Michael Finfer

Treatment of cancer with a ketogenic diet is a form of quackery. See

You should really do a quick search for this stuff before you promote it.

Peter Payne

Dr. Gorkis’ critique of Seyfried’s theories about cancer ends with “Dr. Seyfried might be on to something, but he’s gone a bit off the deep end in apparently thinking that he’s found out something about cancer that no one else takes seriously—or has even thought of before.” He points out that the evidence Seyfried cites does not warrant the level of enthusiasm shown, and mentions several ongoing clinical trials testing the hypothesis–indicating that the hypothesis is legitimate, although as yet unproven. To me, this does not warrant the charge of “quackery”, which implies intentional fraud, and is a charge often levelled with considerable arrogance in contexts where the accuser lacks expert knowledge (not the case in this instance however). However, it does appear to be true that the ketogenic diet’s effect on cancer is not nearly as clear-cut as claimed. At least it does appear clear that it is not harmful!

Michael Finfer

It is harmful when one uses it to treat cancer in place of proven therapies.

That is often left out of discussions of so-called alternative medicine.

Ketogenic diet is also listed on Quackwatch as a dubious treatment.

I think if you talked to quacks like chiropractors or naturopaths, they would object to your characterizing their practices as intentional frauds. They truly believe in what they are offering, much as the Pope truly believes in Catholicism.

Peter Payne

I agree that a merely harmless intervention is harmful if it is used instead of an effective one.

In my experience this is rarely ignored in discussions of alternative medicine.

Your use of the word “so-called” reveals a blanket bias which cannot be called scientific.

I have generally found individuals and organisations specialising in exposing “quackery” to be arrogant and rigid and to lack the intelligent open-mindedness basic to scientific exploration. Data, I respect; generalzed pronouncements, not so much.

Michael Finfer

The problem, of course, is that you are interpreting the need for rigorous evidence before a medical practice is accepted as effective to be rigid.

It is the quacks who lack the open mindedness and the knowledge basic to scientific exploration. They consistently use poor quality, underpowered studies and cherry-picked data to justify their own existence. If you compare the training that some of those folks have and compare it to an actual medical education, the nature of the problem will become clear.

I suggest that you spend some time over at science-based medicine to see what we are really talking about.

Peter Payne

The problems, of course, is that you are making incorrect assumptions in your response to me, manifesting the arrogance I mentioned previously. I won’t bother to correct you, as strongly held emotional biases hardly ever change.

Chris Kavanagh

I’m with Michael here.

Asserting the efficiency of a treatment before having compelling evidence and promoting it over proven treatments is a tried and tested tactic of quackery. As is the tendency to claim that anyone asking for evidence as a cold minded cynic. Nope, it doesn’t work like that, medical claims are easy to make, and it is also pretty easy to find ‘promising’ results from small low quality studies. What is much less common is that the revolutionary alternative treatment actually proves to be more effective in rigorous, good quality and adequate scale trials. If that hurdle is overcome you don’t need to make special pleading arguments about close minded skeptics because the evidence speaks for itself.

Peter Payne

As a scientific researcher who sees first-hand the nitty-gritty of grantsmanship, peer reviews and the competition for money and power, I observe daily the myth of scientific objectivity. As a neuroscientist, I am well aware of the mechanisms of unconscious bias that distort our best efforts to think rationally. Scientists are humans first, and unconscious and institutional bias are facts of life. In a perfect world I would agree with you, but….

The word “quack” is an insult, like “kike”, “slant”, “gook”, and “nigger”. It’s use should be reserved for situations in which there is intentional fraud or deception. Its use in other situations reveals bias.

Chris Kavanagh


That all humans have biases and that science is a human endeavour are true but that doesn’t somehow make all claims and treatments equally valid or imply that modern medicine doesn’t need to bother with high quality trials before treatments are presented as revolutionary. Quackery is a charge labelled at those promoting medical treatments using dramatic claims without the required evidence of efficacy. In this case the charge fits.

Scientists, like all people, are good at compartmentalising and have a tendency to overextend their expertise- see researchers who promote creationism/homeopathy/climate change denial. So while I trust researcher/scientists judgement more than the general public, I am never surprised to see scientists and researchers defend something they have a personal belief in, regardless of the status of the evidence.

Peter Payne

You are probably aware that I did not claim that “all claims or treatments are equally valid”, nor that high quality trials are necessary before promoting some new drug or drug alternative. Straw man.
And, I agree “quackery” is an appropriate epithet for those out to make a buck by ignoring, distorting or concealing evidence. (Parenthetically i note that in all likelihood the actions of drug companies in this vein produce vastly more harm than the likes of Dr. Oz. But I digress.)

I am really trying to talk about the widespread and apparently reflexive emotional dismissal of points of view and frames of reference that fall outside the current accepted views of science. To my way of thinking, the appropriate stance is open-minded curiosity and inquiry rather than reflexive labeling. I do understand that in some situations this would look like “OK, I know quite a lot about this field, and I think it extremely unlikely there is anything to this; can you show me any evidence?” I personally am involved in research into the neuroscience behind Qigong (a form of Chinese traditional health practice). Given that Qigong is based on a theory of “the flow of life energy”, and given that science “knows” there is no such thing, all too often this is dismissed as mere quackery (or other epithet). My own aim has been to translate the traditional Chinese framework into one compatible with neuroscience, and to use that as the basis for RCTs. A rational person would look at my proposals and evaluate them rationally; and that is what has been happening–mainly because over the past 15 years neuroscience has advanced to the point that it can provide a language that can accommodate the phenomena observed with Qigong.. Now, it’s all very well that I have the knowledge and opportunity to do this; but Qigong did not deserve the label “quackery” even before I (and others) began to translate it into acceptable language. You yourself may react to what I am saying with a dismissive putdown ( which would be disappointing) or by acknowledging the validity of what I am suggesting; but hopefully this gives more of an understanding of what I am objecting to.

Chris Kavanagh


You read the article linked to right? You focus on the fact that Gorkis acknowledges there is some plausibility to Seyfried’s hypotheses but did you also note how Seyfried and others have framed his research? Seyfried is quoted directly saying ketogenic diet can replace chemotherapy and radiation for “even the deadliest of cancers” and positing a conspiracy theory about why this revolutionary treatment is not being more widely adopted. That is not simply advancing an alternative hypothesis, it is encouraging quackery, as reflected in the over the top statements (and other treatments) promoted by his most vocal supporters. BTW, I don’t think that financial or nefarious motivations are necessary for something to be quackery, for me all that is necessary is that you are promoting a medical treatment without the necessary evidence to prove efficacy.

And in regards strawmanning, that is not my intention. I am not trying to misrepresent your position but rather highlight the logical conclusion of following a model where the strength and sincerity of the claims are more important than the current quality of the evidence.

I also understand (and share) your concerns about the scientific framework and the conservative nature of currently accepted dogma. Again, as a human effort I completely agree that there will be fallibilities, and there is plenty to criticise about the practices and influence of the pharmaceutical industry in modern medicine as you indicate. However, the thing that separates modern science as a method from other endeavours is that as a system over time it is self correcting because evidence eventually wins out over dogma. This is not akin to other systems of medicine, e.g. blood letting survived for centuries as a popular treatment despite usually being harmful and I am unaware of any TCM practice that was abandoned due to a lack of compelling evidence in clinical trials.

And on that topic in relation to qigong research, I would dispute your characterization that modern neuroscience now ‘accommodates’ the claims concerning Qigong or TCM more generally. I have a long standing interest in such research and that is not my reading of my literature at all. Finding that certain treatments or practices have physiological and neurological impacts or limited health benefits (akin to what you find with any meditation or exercise) is very different from validating claims about energy meridians, the flow of chi, or various claimed health benefits. This is not a dismissive put down either, its simply an assessment of where the current evidence stands.

My experience is that the majority of researchers in this area are not impartial investigators exploring the validity of various claims, but rather individuals sincerely committed to proving that something they believe in is valid and has scientific credibility. Hence, with TCM studies we tend to find a familiar pattern, strong effects from small, low quality studies (particularly those conducted in China) and null, or much weaker effects, in larger better controlled studies (with good placebos). When you take herbal treatments into consideration things change a bit, but that is largely because there are active chemicals in many herbs.

I don’t know anything about your specific research so I’m not directing the above at you directly and I fully anticipate you will disagree with my assessment of current research but I don’t believe our likely difference stems from your being more open minded.

Chris Kavanagh

*Gorkis = Gorski

Guillaume Belanger

Excellent! Now, that’s my area of expertise on weekends 😉 More seriously, I’ve written many things on topics that relate to this. On of them is this one, which considers evolutionary arguments for food choices:

Guillaume Belanger

And on the topic of cancer, I think you will appreciate this one and its follow up:

Michael Finfer

I am not going to comment on the articles about nutrition because that is not my area of expertise except to say that they sound very simplistic, and I am skeptical.

Cancer, however, is within my area of expertise. The article in question was written in 1956, so it, of necessity, ignores everything that we have learned about cancer biology and cancer genetics since than, and we have learned a great deal. The article totally misses the mark in terms of modern knowledge.

I can’t say how “correct” the article was in 1956 because I am not familiar enough with the state of the art back then, but now, I would classify it as a historical oddity that does not offer much to guide us forward. I suspect that I am being generous.

Guillaume Belanger

Finally, if we are interested in optimal metabolic function and flexibility, endurance and strength, then this one is also relevant:

Peter Payne

Many thanks for these informative links!

Guillaume Belanger

Most welcome!

Michael Finfer

So what about modern medicine do you consider to be quackery? The extinction of smallpox? The near-extinction of polio? Antibiotics? The increase in long term survival in childhood acute lymphoblastic leukemia from single digits to near 90%?

Do we know everything? No.

Do we get things wrong? Yes.

Are errors made? Yes.

My take on the stuff about fat is that it is probably one of the things that we got wrong. The real dietary villain, if indeed there is one, is probably going to turn out to be added sugar.

The point is that we are constantly doing research trying to improve ourselves. That is one place where I draw a big distinction between science-based medicine and so-called alternative medicine. Much of alternative medicine seems to be immune to evidence.

What is alternative medicine called when it is backed up be evidence? Medicine. I can’t take credit for that quote.

Dick Burkhart

My older brother swears by a ketogenic diet, also the partner of my wife’s son. I’ve found that a hard core ketogenic diet was too hard for me, but have been successful in getting more fats into my diet and a lot less sugar. For example, I use whipping cream in my coffee and coconut oil as my butter, along with pepperoni sticks, lots of eggs, very low sugar chocolate, etc. This feels healthy.

Jerry Silberman

I trust you are familiar with the work of Weston Price, Nutrition and Physical Degeneration, who made all of this clear in the 40’s, based on decades of studying and comparing indigenous vs. manufactured diets around the world. No one was listening; because his research would have put a lot of so-called medical practitioners, including corrupt quacks like Keys out of business before they got started.

Rolf Muertter

You’d think it couldn’t be that difficult to do a study to see whether the ketogenic diet is effective for cancer treatment. The problem is that it would be way too expensive to do in the US. However, in Turkey there are studies going on right now, and so far the results are dramatic. Unfortunately, even in Turkey some chemotherapy has to be used for legal reasons, but they try to keep it at a minimum.

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