Co-authored by Frank B. Hu, M.D., Ph.D.
Perhaps the most memorably quotable of Michael Pollan's many quotable aphorisms graced the pages of the New York Times Magazine over seven years ago: eat food, not too much, mostly plants. Brilliantly simple, if rather vague, this was a fundamentally valid insight about diet and health then. It still is.
The argument for an emphasis on actual foods rather than manufactured ingestibles masquerading as such garners little opposition from entities not directly involved in selling the latter. Such entities, however, have access to the best marketing talent money can buy. So perhaps we the people can at times be deluded into thinking that a caramel-colored infusion of more sugar than we should consume in a day is an invitation to 23 delightful minutes of frolicking. Perhaps we can at times be duped into thinking that multi-colored marshmallows truly are part of a complete breakfast. But mostly, we think not, and an emphasis on foods and ingredients direct from nature -- in particular vegetables, fruits, nuts, seeds, beans, legumes, and whole grains -- is readily embraced.
The argument for not too much is also relatively devoid of controversy, if only because "too much" is tautologically bad. The relevant measure, the calorie, does engender some controversy, and arguably far too much attention for a simple unit of stored energy, never designed to capture everything important about the quality of foods, nor their capacity to satiate us. We may sidestep the entire controversy here by noting that both the quality and quantity of calories have been shown to matter.
How, exactly, are we to avoid eating too much? We might eat less than we wish, and be hungry all the time, but few of us have the literal or figurative stomachs for that over any length of time. For that very reason, all diets work in the short term, and almost none goes any meaningful distance. But among the many virtues of higher quality, simpler foods is their propensity to fill us up on fewer calories, the very opposite of the willfully engineered incapacity to "eat just one."
Which leaves only the issue of mostly plants. What makes for controversy here is a great deal of heat in the absence of much light.
The heat is generated by the friction of competing claims issuing from an unlikely assemblage of genuine experts advancing some particular, narrowly framed theory (e.g., wheat is "the" one thing wrong with our diets); non-experts with opinions that reverberate comparably through cyberspace; media elements eager to exploit the insatiable public appetite for new and ideally effortless ways to eat ourselves thin and healthy; celebrities who mistake exposure for erudition or merely exploit the prevailing disinclination to distinguish; publishers ever in need of the next best-seller; and a certain concentration of dyed-in-the-wool charlatans.
And then, of course, there is us, in our gullible multitudes, populating a world of tasty, convenient, and ubiquitously cheap foods; a prevailing obsession with sequential fad diets that inevitably fail us; and the penchant for substituting "one thing" that will save us for genuine understanding of a complex, multi-dimensional behavior. Almost any magical promise about losing weight or finding health has us reaching for our credit cards.
This is genuinely tragic, because we have known for literal decades that a short list of behavioral factors, diet salient among them, could cut prevailing overall rates of chronic disease and premature death by an astounding 80 percent. We know this from a vast, diverse, global, impressively unbiased and remarkably consistent literature.
The dietary pattern that figures in this luminous proposition is far less prescriptive than competing claims imply. The currently popular Paleo diet, for instance, does not necessarily diverge from the theme in principle, much as it may in practice, despite the ostensible inclusion of meat. Our Paleolithic ancestors allegedly derived some 50 percent of their calories from diverse plant foods, making their diets "mostly plants" by volume. They ate the meat of wild game animals they had to hunt, and that meat was in turn constructed from a diet of diverse, wild plants. The mass-produced flesh of modern feed animals is all too often constructed out of fare not native to their diets, and so in turn such meat is not native to our own.
The general theme of real food, mostly plants offers no explicit stipulation about sugar or saturated fat; protein or carbohydrate -- despite the zealotry attached to these and other mono-nutrient fixations. Wholesome foods in sensible combinations, as prevail in the world's Blue Zones, seemingly take care of all nutrients, by focusing on none. Such dietary patterns can be low in fat, as vegan and traditional Asian diets tend to be; or high in fat, as Mediterranean diets tend to be. Variations on a common theme nicely accommodate personal preference, allowing us all to find a dietary pattern to love that loves our health back.
How do we know there is such a theme? We have each recently completed and published comprehensive reviews of the scientific literature on the topic of dietary pattern and health. Viewed from that altitude, the similarities of dietary patterns associated with good health are far more noteworthy than their differences. Judicious versions of Asian, vegan, vegetarian, Mediterranean, low glycemic, Paleo diets and more exert their shared benefits by virtue of their shared features, reasonably summarized as: real food, not too much, mostly plants. None prominently features meat or butter despite the current clamoring on that topic; none features highly processed refined carbohydrates or added sugars, either.
That is the verdict of expansive epidemiology, apparent to us both in completely independent reviews, undertaken with different objectives and methods, published in unrelated journals; Annual Review of Public Health in one case, the Lancet in the other. We separately found the same basic truths of modern nutritional epidemiology.
Instead of applying these to good effect, our cultural proclivity for focusing on one food, nutrient, or ingredient as scapegoat or salvation has us exploring every alternative means of eating badly. We have a massive, growing global burden of obesity and chronic disease to show for it. Were we to approach work as we do diet, we would presumably bog down in competing theories about the best ways to succeed while impugning the motives and intelligence of those with opposing views. All the while, few of us would actually acquire an education or get a job. This would do for the economy just what our gullible indulgence in magical thinking about health and weight, and internecine bickering, have done for epidemiology.
There are, of course, barriers to more healthful eating other than our basic understanding. There is the issue of cost, which to some extent is an actual barrier to more nutritious foods, and to a perhaps greater extent is mistakenly perceived as such. It is a barrier just the same. There are many factors that stand between the general public and recommended daily intake of vegetables and fruits. We are not oblivious to these. Our contention, however, is that we will never wrestle effectively with the impediments between here and there until we at least agree we know where "there" is.
As we ponder a seemingly endless parade of "best diet" contestants, we act as if we are answering questions. Instead, we are endlessly questioning the reliable answers that have stood the tests of both time and rigorous scrutiny. These truths suffer from a want of sex appeal, or conspiracy theory intrigue- much like comparably time-honored truths about education and hard work. What we know about the fundamentals of healthful eating is as decisive as it is dull; as redolent with promise as it is devoid of pixie dust.
Our problem is not want of knowledge about the basic care and feeding of Homo sapiens. Our problem is a stunning and tragically costly cultural reluctance -- to swallow it.
Director, Yale University Prevention Research Center
Griffin Hospital; Derby, CT
President, American College of Lifestyle Medicine
Professor of Nutrition and Epidemiology
Harvard School of Public Health
Professor of Medicine
Harvard Medical School