Inevitably this time of year, we are awash in a perennial bounty of advice about how to eat. As one of the annual judges for US News & World Report’s “best diets” release, I am personally tangled up in my own fair share of it.
If you were trying to decide the “best” house to choose for yourself and your family for the rest of your life or at least some meaningful portion of it, I trust we agree that a look inside through just one window would not suffice. You would want a look in every room. Choosing a “diet” for yourself, and perhaps family, should involve much the same- a thorough assessment, taking in all salient considerations and relevant views.
There are, in effect, five distinct windows to the world of food. Only by viewing dietary options through all five can a truly informed judgment be made. In no particular order, the five crucial perspectives on food are:
1) Taste and preference: food as a source of pleasure
2) Our own skin: direct effects of food on our own health
3) All other creatures, great and small: the effects of our food choices on all other life
4) Agriculture and food service: everything to do with the politics, policies, practices, and finances affecting the production, distribution, availability, accessibility, and affordability of our food
5) The view from altitude: the effects of our dietary patterns on the planet itself
In 2020, the idea that we can offer guidance about healthful eating with a view through just one window is obsolete. We live in an era dubbed the “Anthropocene,” meaning the age during which human activity has become the dominant influence on planetary systems and the environment. Among the domains of greatest influence is diet, which in turn influences everything about how food is sourced. We can use the term “dietary patterns” to connote everything involved in making specific food options available to us in our hungry multitudes.
Let us, accordingly, look through those five windows at food. Food should certainly be a source of pleasure, but what tastes good is largely a matter of familiarity. We have been conditioned by those who profit from the corruption of our palates to favor ultra-processed junk food. We can rehabilitate our taste buds, and learn to love food that loves us back.
As for our own skin, there are many reasonable and related variants on the theme of “best” human diet. That theme is a plant-predominant diet of mostly whole and minimally processed foods; a diet of abundant vegetables, fruits, whole grains, beans and lentils, nuts and seeds- and plain water preferentially for thirst.
The best diet for our fellow creatures is, obviously, one that does not involve their abuse, incarceration, and slaughter in heartless factory-farming operations. It is one that does not ravage vital ecosystems and assault biodiversity.
The best diet should be supported by agricultural practices, not undermined by them- but there is a potential tautology in the mix here. Policies and practices of the food supply take shape around the food demand. History suggests the one most reliable way to alter everything about the food supply- is for the demand to shift.
Finally, there is the window to the world at large. Dietary patterns at the scale of nearly 8 billion hungry Homo sapiens (N.B.- the uncontrolled growth of the overall human population is, clearly, an existential threat in its own right- and arguably, the root cause of all others) are a major cause, if not the major cause, of global aquifer depletion and declining access to fresh water. Dietary patterns at the global scale are a major cause of mass extinction. They are a major contributor to greenhouse gas emissions, and thus, climate change.
Our dietary inclinations, and specifically our taste for beef, are the reason the Amazon is being razed. Our penchant for processed foods and their reliance on palm oil is why rainforest in Borneo is suffering the same fate.
In a world where the very habitability of Australia appears to be in question; where polar ice caps and glaciers may be historical curiosities; where our dietary inclinations are the reason for rainforest devastation- we health professionals must all rally to make it emphatically clear at every opportunity that there is no “best” way to eat for our own sakes that does not address the sake and fate of forests, glaciers, aquifers, and life here in all of its wondrous, intricate connections. To speak of “best” diets for human health in isolation implies, by omission, that eating to avoid mass extinctions, the abuses of factory farming, and the devastation of vital ecosystems...is all separate from considerations of our personal interest.
It is not. In 2020- now- the idea that we can eat for our own health while ignoring the health of the planet is, quite simply, extinct.
This is true because of indirect effects. The fragile state of the Earth makes clear that our interest in human health cannot -ever again- be divorced from planetary health. There are no healthy people, and no sustainable, healthful diets, on a ruined, ravaged planet. If we talk about these as separate topics, we propagate the fraught fantasy that diet for us, and diet for the planet may be unbundled in practice. They of course may not.
This is also true because of direct effects. Climate change is fostering the emergence of new infectious diseases, and expanding the geographic footprint of others. Floods and fires, famines and droughts are upending human lives, and taking them, with increasing frequency, right now. None of this tale is theoretical. The dangers are present, and clear.
Across the expanse of relevant views, then, there are many closely related variants on the theme of “best” human diet. There is, nonetheless, one timely truth for all to swallow.
In this, the Anthropocene era, we can no longer define “best” within the bounds of only our own skin. Persist in that delusion, and we risk chewing through, and spitting out, much of what matters most about diets best for our own food supply, the rest of life, and this planet in all the ways we have been privileged to know it.
Perhaps that’s hard to swallow; perhaps that sticks in the craw. I suggest we overcome that, and digest a modernized, more holistic concept of “best” diet nonetheless. For if we don’t, and soon- there may little that is nourishing left to swallow down here.
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.