Diet in a taubesy-turvy world
About the last thing the world of nutrition needs is rebuttals about details to rebuttals about details that distract us all from the big picture. We have been missing the dietary forest for the truculent trees for decades already, and the result is the dark wood of modern epidemiology in which millions of us succumb unnecessarily to obesity and chronic disease, and in which millions upon millions of dollars are made by Big Food at the expense of our health, and as a tax on our punctilious gullibility.
An endless parade of competing claims about details, inattentive to the fundamental truths of good eating, is about the last thing we need. But it is, inevitably, the first thing we see when we tune in each day to the news, or log on each day to the Internet. This past weekend was no exception.
Before getting to that, let's pause momentarily to address those alleged "fundamental truths." Are there, indeed, fundamental truths about eating well? In my opinion, there absolutely are. While all human knowledge is imperfect and subject to the ebb and flow of new evidence, and diet is far from an exception, we are obligated at times to contend we actually know enough to act accordingly. Were residual uncertainties about diet allowed to forestall all action, we would not be capable of feeding our dogs, our cats, or our tropical fish. We don't have perfect knowledge of their dietary needs either, but we know enough to feed each its fundamentally appropriate diet. There is no reason for Homo sapiens to be an exception.
We have known enough for decades to use diet, in conjunction with other aspects of lifestyle, to prevent roughly 80 percent of all serious chronic disease, i.e. heart disease, cancer, stroke, diabetes, dementia and more. If that is not an invitation worth accepting, it's hard to imagine what would be.
Further, those same fundamentals are supported by a vast volume of diverse research, including intervention trials, and represent the aggregate weight of evidence. They have stood the test of time. And when applied by populations in the real world, they contribute to exceptional longevity, exceptional vitality, lifelong weight control and the predicted prevention of preventable disease.
What are the fundamentals? Michael Pollan expressed them as, "Eat food, not too much, mostly plants." With a bit more of a nod to the potential for variations on a common theme, Frank Hu and I said, "Eat wholesome foods in sensible combinations," with a bow of thanks in Pollan's direction.
More specifically, a diet is apt to be good if comprised principally of foods direct from nature, unprocessed or minimally processed. A diet of mostly plants is warranted for the health of people and planet alike. Vegetables and fruits, nuts and seeds, beans and lentils are consistently and conclusively associated with health benefits, and thus should figure prominently in any diet directed at health. The same is true of whole grains for those not intolerant to them, although that topic has been regrettably confounded by self-serving noise.
Once a diet is made up mostly of vegetables, fruits, beans, lentils, nuts, seeds and (for most of us) whole grains, there simply is no way left for it to go very far wrong. Focus on any given nutrient, and the diet fabricated around it might be good, but recent history suggests it will likely be an utter boondoggle, playing only to the interests of predatory profiteers. In contrast, get the foods right, and all nutrients – both those we think about, and those we don't – sort themselves out with considerable reliability.
These fundamentals of healthful eating do not require, and in fact discourage, a focus on any given macronutrient class. Because all such diets are rich in plant foods, and all plant foods are carbohydrate sources, such diets are inevitably at least moderately high in that variety of "carbohydrate." So what? Foods from lentils to lollipops are carbohydrate sources, but with vastly differing implications for health.
Such diets may be quite low in total fat, as vegan and some traditional Asian diets tend to be; or rather high in total fat, as some variants on the Mediterranean diet theme tend to be. Again, so what? Both patterns get the fundamentals right: wholesome foods, mostly plants, in sensible combinations. We tried a fixation on total fat, and all it got us was Snackwell cookies, followed by "butter is back." Both are silly distractions.
An embrace of the fundamental truths of eating well involves an emphasis on foods rather than nutrients. It rests on the weight of evidence, and on a massive, global consensus of expert opinion about what that evidence means. It certainly allows for the pursuit of answers to many good questions that beckon, but renounces the scientific analogue to the non sequitur: the seemingly erudite answer to a contrived, misguided question. These have been diverting us for far too long as is.
An example is: "Do calories count?" The cottage industry that has developed in response to that unhelpful question has been propagating profit for the few and confusion for the many for years. The question seems erudite, challenging the stodgy old views of energy balance, and replacing them with a primer on endocrinology. But before you get huffy, take a calming breath and ask yourself: Did you ever, for a second, think that all calories were created equal? Did you ever think that equal numbers of calories from foods as diverse as lentils and lollipops, pinto beans and pastrami, were equally filling? Did you ever once think that the amount of eating you did during any given snack, meal or day had nothing at all to do with what you were eating?
In 25 years of patient care, I've had the opportunity to address such issues with thousands and thousands of people, and don't know one who answers "yes" to the above. In other words, everybody knows that both the quality and the quantity of calories matter, and that the former exerts a major influence on the latter. Not only does everybody know that, but we have all witnessed it being advertised directly at us, courtesy of Lay's potato chips: "Betcha' can't eat just one!" We have never heard such a marketing slogan for Granny Smith apples, and for reasons that are self-evident.
The reality is that no one was confused about the nature of calories in the first place. Of course they count; we can lose weight on small amounts of junk or gain it on an excess of "good stuff." But in the real world, how much we eat is mightily influenced by what we eat. Those eating good stuff are far less likely to overeat than those eating junk. We know even, courtesy of Michael Moss among others, that many of our dubious but tempting food choices are willfully engineered to maximize the calories it takes to feel full. Calories count, but so do our food choices. And yes, those influence hormonal responses, too, and yes, those are important – notably, insulin. But only those peddling their own brand of renegade genius have any basis to think that a choice must be made between high-quality foods that foster satiety and hormonal balance, and the quantity of calories. These have always gone together.
All of which brings us back to rebuttals of rebuttals, and the dire portents of that redundant percussion.
Recently, Dr. Kevin Hall at the National Institutes of Health conducted a small, short-term, but highly-controlled study of varying macronutrient intake with fixed calories among human adults on a metabolic ward. His study showed preferential loss of body fat when dietary fat was restricted. The study was not, however, intended as a public inducement to restrict dietary fat. It was designed as a rebuttal. The science writer, Gary Taubes, had contended in rather public venues that fat could only be lost by restricting carbohydrate, and lowering insulin levels. Dr. Hall, an expert in energy balance, thought otherwise – and designed a study to test the proposition. The results have been widely circulated.
Inevitably, and regrettably, this has induced Mr. Taubes to defend his disproven assertion, taking advantage of the once rarefied real estate doled out somewhat indiscriminately these days by The New York Times. Taubes references the Hall study, but misrepresents it. Dr. Hall did not set out to establish a diet people could follow for a lifetime; he set out to challenge a very specific assertion propounded by Mr. Taubes himself. The study selectively shows that the assertion that weight loss is exclusively about carbohydrate and insulin is false.
Taubes goes on to suggest that hunger is the neglected consideration in the world of weight control. He conveniently fails to mention the veritable mountains of scientific work devoted to that very topic. Michael Moss is not mentioned; Brian Wansink is not mentioned; David Jenkins is not mentioned; Barbara Rolls is not mentioned; and so on. Failure to consider hunger, and satiety, during a weight-loss attempt may be characteristic of the false hopes of dieters looking for a quick fix, and the slick hucksters who peddle the same – but pertains to no serious researcher I know. This is the classic "straw man" tactic, where the position being refuted isn't a position held by any reputable person in the first place. Satiety is a salient consideration in all work on weight loss worth a look in the first place.
The Taubes' rebuttal to the Hall rebuttal runs off the rails in other ways as well. The column insinuates, without quite saying it, that carbohydrate restriction induces weight loss without restricting calories, but this is not so. Carbohydrate restriction ineluctably reduces calorie intake, since carbohydrate is the main source of calories in all omnivorous diets – that of Homo sapiens included. In every study of, for instance, the Atkins' diet that I have examined closely, that dietary assignment resulted in lower calorie intake than the other groups.
I hasten to clarify that I am not interested in advocating for the restriction of one macronutrient rather than another. I am interested in wholesome foods in sensible combinations that can allow people to lose weight, and find health. I am interested in variations on the theme of eating well that can empower people to love food that loves them back. I am interested in wholesome foods that help people achieve satiety with a reasonable intake of calories, and the avoidance of willfully engineered junk designed to do the converse. I am interested in sustainability, which arguments for eating more meat ignore entirely – as did Mr. Taubes in his column. I am interested in using what we know to advance the human condition, rather than pretending that progress must forever await the erudite answer to a silly question.
Calories count. So does hunger. Weight can be lost cutting carbohydrate, or fat, dependently or independently of the direct actions of insulin. None of this alters the fundamentals of healthful eating actually associated, in actual people in the actual world, with the very outcomes we all desire: vitality, longevity, weight control without want and even – importantly – pleasure from food.
Alas, we don't live in that world. We live in a world of Taubesy-turvy nutrition, perennially confused by the claims and counter-claims; too dizzy to see the forest through the trees, unable to find our overdue way out of the dark wood.