Tag Archives: high-fat low-carb diet

Does The World Need Any More Diets?

Recently I came across a new book called The Microbiome Diet. It is based on the idea that the colonies of bacteria in our guts are “the secret to healthy weight loss and to feeling healthy, energized, optimistic, and at the top of [our] game.” Author Raphael Kellman prescribes a three-phase plan that entails including prebiotic and probiotic “superfoods” such as yogurt, sauerkraut, garlic, and tomatoes in every meal.

Like most inventors of new diets, Kellman argues that his diet is needed because existing diets are based on bad information and consequently don’t work. He writes, “I believe that this book will challenge everything you know about the causes of obesity—and about the kind of diet that can successfully overcome it.”

It’s easy to laugh at Kellman’s suggestion that his diet is the only true solution to the problem of diet-related health problems. Only a few hundred people in the entire world are currently following it and it’s unlikely that more than a few thousand ever will. The notion that the only diet that’s truly good enough for humans would come along for the first time in 2014 and then pass into oblivion having made barely a ripple seems far fetched. But what about some of the other new diets, the ones that have caught on in a big way, such as the Paleo diet and the gluten-free diet and the high-fat version of the low-carb diet? The creators of each of these diets has also argued that his is needed because no previously existing diet was good enough to yield optimal health. Is any of these diets really needed? No.

What allows the creators of such diets to convince many people that a new way of eating is needed is the fact that the incidence of diet-related chronic diseases is higher than it’s ever been. This is clear proof, they say, that existing diets don’t work. Except it isn’t. For if all currently existing diets were ineffective in producing good health, then everyone would be unhealthy. But while most American adults are fat and doomed to die from heart disease, diabetes, or another disease affected by diet (Alzheimer’s, some cancers), in absolute numbers there are lots of healthy people. Indeed, virtually everyone who actually makes an honest effort to eat healthy by any definition and sustains this effort throughout life is rewarded with robust health. The people who end up fat and saddled with chronic disease are the majority that doesn’t even try to eat healthy.

If we look at the small sliver of the population that sustains its efforts to eat healthy, we find that many existing diets work perfectly well. People who start and stay on sensible versions of vegetarian, Mediterranean, low-carb, low-fat, clean-eating, locavorian, agnostic, and other diets are typically hale and hearty. The problem is not, as the inventors of new diets assert, that there are no good options. The problem is that only a tiny fraction of us takes advantage of the many good options available to us.

Here’s another way to look at it: In 1950, virtually no one was following anything we would recognize as a microbiome diet or a gluten-free diet or a Paleo diet or a high-fat/low-carb (HFLC) diet because A) these diets hadn’t been invented yet and B) they are not culturally normal, so it was unlikely that some random weirdo would eat by the rules of any of them accidentally. Thus, to argue that any of these new diets is needed because no previously existing diet was good enough is essentially to argue that no one living in 1950 was healthy.

Of course, advocates of the Paleo diet argue that their way of eating is not new at all but a reversion to “the original human diet,” and some proponents of the HFLC diet do the same. This argument represents a complete inversion of the truth. Paleo dieters eat the same modern foods that everyone else eats, all of which are only distantly related to the foods eaten by Paleolithic humans. The only difference between the way the average Paleo dieter eats and the way his next door neighbor eats is that the Paleo dieter eschews some foods, such as dairy, that his neighbor eats. This combination of modern foods and selective exclusions is fundamentally novel. When Loren Cordain published The Paleo Diet in 2002, the eating program unveiled therein was the world’s newest diet. If it resembled primitive diets more than other modern diets did, it was only on the most superficial level.

In any case, a more important way in which Paleo diet doctrine stretches credulity is the same way that most other new diets do. According to Paleo doctrine, humans stopped eating right at the dawn of the agricultural revolution some 12,000 years ago. Therefore, to argue that the Paleo diet is needed because no post-Paleolithic diet was good enough to support optimal health is essentially to argue that there have been no healthy humans for the past 12 millennia.

Let me be clear: I’m not suggesting that all new diets are bad. I think most of them are good. Humans can thrive on a wide range of diets, so it’s not hard to come up with a novel diet that respects the few nutritional laws that can’t be broken without repercussions for health. But no new diets are needed. The current epidemic of diet-related diseases will not be solved by the discovery of the first and only diet that really works. Good-enough diets have always been available. Until scientists invent a pill that makes people crave broccoli and gag at the sight of french fries, each of us is on his own to solve the problem individually by selecting one of the many good-enough diets and sticking with it.

Sour Grapes Syndrome

Everyone knows Aesop’s fable about the fox and the grapes. A fox is walking along in the forest when he spots a juicy bunch of grapes hanging from a branch. He leaps upward and tries to snatch the fruit between his teeth but he misses. He tries a second time and misses again. After a third miss he gives up and slinks away, muttering, “They’re probably sour anyway.”

Psychologists have a term for what the fox was experiencing: cognitive dissonance. The term refers to any situation where reality contradicts one’s preferred self-conception. The natural response to such situations is to change one’s beliefs about reality in such a way as to preserve one’s self-conception. In Aesop’s fable, the fox decided he never wanted the grapes in the first place so that he would not have to admit he couldn’t jump high enough to get them.

There is an epidemic of “sour grapes syndrome” (as I call it) in endurance sports today. Its victims are endurance athletes who cannot cope psychologically with being slower than they would like to be and who resolve this cognitive dissonance by replacing the goal of doing their sport well with that of doing it “right.” The syndrome is being spread by various movements that promote alternative methods that are contrary to those practiced by the most successful athletes. Examples include barefoot running, interval-based training, and high-fat diets.

By latching onto one of these methods, athletes can claim a kind of victory over superior competitors. “You may have finished the race ahead of me, but you were heel striking whereas I was forefoot striking, and since the real objective of racing is not to finish as quickly as possible but to exhibit the best form, I actually beat you.” That sort of thing.

It sounds infantile—and it is—but it’s a widespread mentality. I hasten to add, though, that the vast majority of slower endurance athletes are perfectly okay with being slow. They are focused on improving their own best times and couldn’t care less how many people finish in front of them. It’s only a small minority that is eaten alive by its slowness to such a degree that it feels compelled to change the rules of the game. Interestingly, but not surprisingly, most endurance athletes who suffer from sour grapes syndrome are male.

Elite athletes never go in for the alternative methods, for a couple of reasons. The first is obvious: As the fastest athletes, the elites do not experience the gnawing envy of faster athletes that is at the heart of sour grapes syndrome. The second reason is that the alternative methods don’t work as well as the dominant best practices. Athletes whose livelihood depends on being as fast as possible can’t afford to fool around with inferior methods the way slower athletes with alternative goals can.

I try not to judge athletes with sour grapes syndrome, but I do feel compelled to speak up when a particular movement becomes visible enough that it begins to win converts among athletes who are not, in fact, wracked with jealousy of faster athletes but who simply don’t know any better. There are signs that the high-fat/low-carb diet trend has passed this tipping point. I’m hearing from more and more athletes whose training has been ruined by a switch to a HFLC diet that was precipitated by an earnest wish do get faster and not by a desire to have something to hold over faster athletes who eat lots of carbs.

So I’m standing on my soapbox and putting a bullhorn to my lips to spread the message that HFLC diets are not good for most endurance athletes. They reduce tolerance for high-intensity training and impair performance in all races except perhaps ultra-endurance events such as 100 km trail runs.

The latest scientific proof of this already well-proven fact comes from a new study published in the journal Nutrients. Polish researchers placed eight mountain bikers on each of two diets for four weeks in random order. One diet was high in fat and low in carbohydrate, consisting of 15 percent carbohydrate, 70 percent fat, and 15 percent protein. The other diet was balanced, consisting of 50 percent carbohydrate, 30 percent fat, and 20 percent protein. At the end of each dietary intervention, the subjects underwent three days of physiological testing that culminated in a 90-minute stationary bike ride at 85 percent of lactate threshold power followed by a 15-minute time trial.

Before I share the results, let me pause to note that the founding principle of HFLC diets for athletes is that carbohydrate does nothing good for the body either at rest or in motion. Proponents of these diets believe not only that eating carbohydrate is fattening and otherwise unhealthy, but also that burning carbohydrate during exercise hurts performance by hastening exhaustion. The rationale for prescribing HFLC diets for endurance athletes is that they increase the reliance of the muscles of fat and decrease their reliance on carbohydrate, thereby enhancing performance.

The Polish researchers who conducted the study in question found that the HFLC diet did everything it was supposed to do physiologically. For starters, it made the subjects leaner. After four weeks on the balanced diet, the subjects’ average body fat percentage was 14.88. After four weeks on the HFLC diet it was 11.02. The HFLC diet also increased fat burning during exercise. Scientists use a measure called respiratory exchange ratio (RER) to quantify the relative contributions of fat burning and carbohydrate burning to muscle work. The higher the number, the more carbs are being burned relative to fat. On average, the subjects’ RER during exercise was 6 percent lower on the HFLC diet than on the balanced diet.

There was only one problem. All of these “favorable” physiological changes were associated with a significant loss of performance. On the balanced diet, the subjects generated 257 watts at lactate threshold intensity and 362 watts during the 15-minute maximal effort. On the HFLC diet, these numbers dropped to 246 watts and 350 watts. According to the study authors, the cause of the loss of performance capacity on the HFLC diet was impairment of the muscles’ ability to burn carbs. Oops!

So that’s the science. But what about all those social media testimonials you see from athletes who have made the jump to HFLC diets? Let me answer this question by asking another: How many times have you seen testimonials for weight-loss pills and muscle-building supplements that don’t really work? I’m not one to dismiss all anecdotal evidence out of hand, but when anecdotal evidence contradicts the results of formal scientific inquiry, it should be given very little weight.

When the barefoot running fad was raging a few years back, many runners who ditched their Brooks Beasts for Vibram Five Fingers reported that going natural had made them better runners. But I never encountered a single barefoot runner who, when pressed, could point to a big new PR that was set soon after the switch. It became clear to me that what these runners really meant when they said that barefoot running made them better was that it hadn’t made them worse.

I do believe there is a minority of endurance athletes who don’t get worse on HFLC diets. I don’t believe there are any who get better. And I believe that most runners who try HFLC diets don’t really do it for the sake of improving, although they convince themselves otherwise. If you really care about your performance, don’t go on a high-fat/low-carb diet… or run barefoot, or switch to an interval-based training approach, or do anything else that race winners don’t do.

Don’t Blame the Dentist for Your Cavities

Among the more absurd ideas being peddled by certain diet cults these days is the idea that mainstream guidelines for healthy eating are directly responsible for the ongoing American epidemic of metabolic syndrome. If you know a hardcore Paleo dieter or a high-fat/low-carb eater, then you probably know someone who believes this astoundingly ridiculous notion, having learned it from Denise Minger’s book Death by Food Pyramid or from Paleo guru Robb Wolf’s blog ravings or from some other mouthpiece of Paleo or HFLC dietary doctrine.

The logic of the argument is well summarized in the promotional copy for Minger’s opus. Here’s a sample: “Shoddy science, sketchy politics and shady special interests have shaped American dietary recommendations—and destroyed our nation’s health—over recent decades. The phrase Death by Food Pyramid isn’t shock-value sensationalism [no, of course not], but the tragic consequence of simply doing what we have been told to do by our own government—and giant food profiteers—in pursuit of health.”

If your IQ is higher than 85, you don’t need me to tell you that this line of reasoning depends on one very big and very false assumption: namely, that most Americans actually obey mainstream dietary recommendations. In fact, the diet of the average American is very nearly the opposite of what is recommended in official resources such as the U.S. government’s Dietary Guidelines for Americans.

Among these guidelines is the familiar recommendation to consume at least five servings of fruits and vegetables daily. Only 11 percent of Americans meet this requirement. The American Heart Association recommends that adults consume no more than six teaspoons of added sugar each day. The average American consumes 22 teaspoons of added sugar each day. The USDA’s MyPlate program advises people to get at least half of their grains in the form of whole grains. Forty percent of Americans never eat whole grains. The American Heart Association recommends that fish be eaten at least twice a week. Only one-third of Americans eat fish even once a week. And so on.

Not only do most Americans fail to follow mainstream dietary recommendations, but they also don’t even know what these recommendations are—or that they exist at all. According to a large scientific survey conducted a few years ago, fewer than half of American adults have ever heard of the Dietary Guidelines for Americans and less than 40 percent are aware that these guidelines include the recommendation to eat five or more servings of fruits and vegetables daily.

Blaming mainstream dietary recommendations for the high rates of obesity, heart disease, and type 2 diabetes in America is logically equivalent to blaming dentists for the high rate of tooth decay among our citizens. The American Dental Association recommends that people brush their teeth at least twice a day and floss at least once a day. Only 53 percent of Americans follow the first of these recommendations and even fewer of us follow the second. Ninety-two percent of American adults have decayed teeth, despite almost universal exposure to the ADA’s recommendations for dental hygiene. So do we blame the dentists? That wouldn’t make much sense, because the incidence of tooth decay is much lower among those who actually do follow ADA guidelines. Similarly, only a fraction of Americans follow mainstream dietary recommendations, but those who do are much healthier than those who don’t.

Proof that following mainstream nutritional guidelines results in much better health than does eating like the average American is piling up rapidly. Some of the best recent evidence comes from a study associated with the ambitious Dietary Patterns Methods Project. This project is investigating the health effects of various eating patterns that are consistent with mainstream dietary guidelines. The first study to issue from the project measured the degree to which the diets of 424,000 older men and women conformed to each of four indexes of healthy eating—the Healthy Eating Index 2010, the alternative Healthy Eating Index 2010, the alternative Mediterranean Diet, and the DASH diet—and correlated this data with death risk over a 15-year period.

The mortality rate for those whose eating patterns conformed most closely to each of these indexes was significantly lower than it was for those whose eating patterns conformed least closely. Since the subjects were American, it is safe to assume that the men and women who had the lowest scores on these indexes tended to eat the typical American diet. According to this study, the people whose eating habits fell furthest outside official recommendations were up to 28 percent more likely to die of cancer or heart disease between the ages of 62 and 77 than were those who ate according to mainstream dietary guidelines.

Despite such evidence, Paleo and HFLC diet advocates continue to conflate mainstream dietary recommendations with the typical American diet. They do this most insidiously with their use of the term “standard American diet” (or SAD—get it?) to refer to both the way the average American eats and the way mainstream nutrition scientists advise people to eat.

Consider these sentences from “Paleo Runner” Aaron Olsen’s review of my book, Diet Cults: “Considering the fact 2/3 of Americans are either overweight or obese, I fail to see how mainstream recommendations such as the SAD should be used as a template for an optimal eating strategy. The reason diet fads are so popular in the first place is because the SAD has failed us so miserably.”

Here we have an egregious misrepresentation of the “agnostic healthy eating” guidelines I present in the book, which are based on mainstream nutrition science, not on what the average American eats. But is this misrepresentation deliberate or merely a consequence of the reviewer’s own prior brainwashing? I won’t hazard a guess, but it is evident that some high priests of the Paleo and high-fat/low-carb diets choose to conflate mainstream dietary guidelines with the standard American diet despite knowing full well that the two are worlds apart. In so doing they betray not only a startling lack of intellectual integrity but also a troubling assumption about the intelligence of the eating public.

Here, in essence, is what these folks expect you to believe: that if a typical American eater, who spends $1,200 annually on fast food, were to hire a registered dietitian to help him get healthier, the R.D. would make no changes to her client’s diet.

For the record, I don’t think you’re that stupid.