I can’t seem to make it through a full conversation these days without some variant on the theme of: “so what about that keto diet, anyway?” Perhaps that’s an occupational hazard of being a “nutrition guy,” but I suspect you are tripping over those discussions, too. Such is the nature of diet fads.
So, then, what about the ketogenic diet? As best I can tell, the current fascination is fueled by the following attributes, promised or implied by those peddling the diet in one form or other: (1) it’s new, cutting edge, dietary magic; (2) it offers advantages over all prior, old-fashioned, non-magical approaches for weight loss; (3) it offers advantages over all non-magical approaches for health and performance; and (4) you can really live this way.
You are probably not surprised to hear- perhaps from me in particular- that #2 and #3 are demonstrably false, and #4 is unsubstantiated, wishful thinking. We will return to those. But perhaps you’ll be surprised to learn the lie of #1: the diet is anything but new.
Here are photos of the cover and p. 28 from my copy of “Dr. Atkins' NEW Diet Revolution!”- with a copyright date of 1992:
So- OK- the ketogenic diet is 26 years old. What’s a couple of decades among friends?
Not so fast. Dr. Atkins’ “NEW” diet revolution of the 1990s was published as Dr. Atkins’ just plain diet revolution of the 1970s. Little is different between the two versions, but for “NEW” in the title, and the hope that 1990s book buyers had forgotten about prior attempts to sell them this same stuff. They had.
But this means that the ketogenic diet has been with us for nearly 50 years. And, even that is only its more recent incarnations- it has prior versions of itself going back much further. But we can settle for: we’ve had recurring exposure to this diet for the past half century.
So, the “keto diet,” by other names, is not new. Does that reliably disprove, all by itself, the claims- explicit or implied- of the diet’s magical advantages?
Yes, actually, I believe it does. If you do not, a thought experiment may help persuade you.
Let us imagine a magical formula for human flight. I do not mean of the plane or helicopter variety; I mean just you, in your altogether. I have no idea what that formula might be: concentrate and levitate; the right yoga pose; vigorous wiggling of your nose; burping six times in a row with real conviction? Let’s just accept that it is… something.
That formula is introduced in a book in the 1970s that does only moderately well. It is re-introduced in the 1990s in a book that calls it new, gets a boost from some bully pulpit, and sells tens of millions of copies.
If the magical formula worked, what are the odds that very few people today would be flying? Wouldn’t you fly if you could, and if a magical formula a mouse-click away at Amazon made it nearly effortless to do so? Who wouldn’t?
Perhaps you are thinking that flying is just implausible for humans. Yes, I agree- but frankly, alas, so is weight control in a modern culture that combats willfully addictive junk food and multi-colored marshmallows as part of a complete breakfast with a never-ending sequence of silly fad diets. Magic is implausible in either case.
But that’s not the point. The point is that if we had epidemic human flightlessness, and a VALID magical formula for flight were introduced decades ago, a lot of us would be flying around today. If no one IS flying around today, there was no magic in the formula.
Similarly, if there were any merit at all to the implied, magical advantages of the ketogenic diet, there would be lots of thin people living the life and smirking at the rest of us. Instead, obesity rates have only gone up, and markedly, since the Atkins’ heyday of nearly two decades ago.
Just for completeness, let’s add the same analogy, pointed the other way. Imagine if in, say, 1997, a magical formula were introduced for composing a thought in your hands, and beaming it to any single person of your choosing, anywhere on the planet. How many of us would be doing that now?
Well, that one was really introduced, in the form of mobile phone text messaging. And the answer is: just about everybody! When a magical formula for something most of us want- to be lean, to text, to fly- is actually introduced, it becomes the cultural norm. When it doesn’t become the cultural norm, it’s because there was never really any practical magic in the first place. Quite simply, if the keto diet offered any of the lasting advantages fueling the current round of hype, we would all have been living that way since long ago.
It does not.
The diet is claimed to offer weight loss benefits. Sure, you can lose weight, improve your cardiometabolic profile, and even potentially reverse conditions like type 2 diabetes using a ketogenic diet. But that is only in the short-term, and in competition with the prevailing “see food” (I see food, and I eat it) diet. Everything beats that. Besides, some very dubious propositions can lower weight and blood sugar in the short term; cholera, amoebic dysentery, and a crack cocaine binge all come to mind.
There is no evidence that the keto diet is superior to any of the dietary variants established to defend against obesity and chronic disease not just in the short term, but over time. In general, direct comparison of low carb to alternatives shows no advantage, even among those genetically predisposed to reveal one.
There are no long-term human studies of the keto diet, and no free-living, healthy human population lives this way. We thus have no evidence that the diet can be maintained, that it fosters health over time, or even that it is safe. Contrast that with the dietary variants of the Blue Zones, known to foster vitality and longevity, generation after generation.
There is a valid claim that ketosis suppresses appetite. But so, too, do amphetamines, influenza, salmonella, and nicotine, to name a few. If we are all inclined to do something retro and seriously misguided to suppress our appetites, we might as well all go back to smoking.
To be fair, though: absence of evidence is not evidence of absence. None of what I’ve cited above proves that the keto diet is bad for human health (although I certainly suspect it is). It simply proves that all of the claims of its magical advantages are contrived or confabulated, marketing collateral, not facts. You are, once again, being suckered.
As for athletic performance, there the evidence is rather damning. World-leading researchers in nutrition for optimal human performance have studied degrees of carbohydrate restriction, and found that they tend to compromise peak performance, compound muscle injury, and delay recovery. A prominent colleague in this area recently told me directly that the global community of experts in sports nutrition is uniformly opposed to carbohydrate restriction in general, and the ketogenic diet in particular, based on the data currently available.
And let’s be sure to acknowledge, as the ominous mayhem of climate change is ever less theoretical, ever more up close and personal for us all, that this diet in its standard incarnation is bad for the planet, and if adopted at scale, calamitous. In theory, at least, there could be adaptations of the diet to circumvent that problem, but it’s the reconciliation of a square peg to a round hole.
Most notably, the diet simply isn’t remotely new; it has had the opportunity to impress, delight, and impart its alleged benefits to us for nearly 50 years. Hot concept though it may seem at the moment, the keto diet is the leftovers of yesterday’s fad, renamed, and reheated. Reach for cutlery in that context as the spirit moves you.
David L. Katz, MD, MPH, FACPM, FACP, FACLM, is the Founding Director (1998) of Yale University’s Yale-Griffin Prevention Research Center, and current President of the American College of Lifestyle Medicine. He has published roughly 200 scientific articles and textbook chapters, and 15 books to date, including multiple editions of leading textbooks in both preventive medicine, and nutrition. He has made important contributions in the areas of lifestyle interventions for health promotion; nutrient profiling; behavior modification; holistic care; and evidence-based medicine. David earned his BA degree from Dartmouth College (1984); his MD from the Albert Einstein College of Medicine (1988); and his MPH from the Yale University School of Public Health (1993). He completed sequential residency training in Internal Medicine, and Preventive Medicine/Public Health. He is a two-time diplomate of the American Board of Internal Medicine, and a board-certified specialist in Preventive Medicine/Public Health. He has received two Honorary Doctorates.