For all his contributions to science, controversial and otherwise, in modern context Sir Isaac Newton is most indelibly associated with one rather succinct assertion of physical truth: For every action, there is an equal and opposite reaction.
Were the governance of this third law of thermodynamics limited to the domain of physics, as was Newton's apparent thinking on the subject, we would spare ourselves a great deal of grief. Unfortunately, the laws of thermodynamics are in turn, it seems, subject to the law of unintended consequences. So it is the hegemony of the third law has trespassed into the realms of human psychology and sociology, and public health is much the poorer for it.
I have been lamenting for years that not only have we managed to be serially wrong about nutrition, we have been wrong about how we went wrong. When, for instance, the salient guidance was to “cut fat,” it was wrong in some of the particulars. Not all dietary fat is created equal. Not even all saturated fat is created equal. But any deficiencies in the admonition were greatly subordinate to its willful exploitation for profit.
What do I mean? When those in the vanguard of the movement first suggested reducing dietary fat intake, there was really only one way to get there from here: Eat more vegetables, fruits, beans, lentils, and whole grains. Since those foods are salient, if not overtly predominant, in diverse diets around the world associated with the greatest longevity and vitality, this could only have done us good. But we never had a moment to renounce mounds of salami to make room for more spinach, or to get a bit more of our protein from pinto beans and a bit less from pepperoni. Before ever we paused to consider such judicious opportunities, Snackwells had been invented, and the era of low-fat junk food began.
No nutrition expert ever said: Eat fat-free junk food, and all will be well. But that's what we did. And these days, we act as if that is somehow a failing of epidemiology, rather than assigning blame where it belongs: those elements of supply willing to subvert public health messaging for profit, and those elements of demand willing to believe that what seemed too good to be true was true nonetheless. Eating cookies will make me healthy? Bring ‘em on!
Regrettable as that digression was, it might have been worth it had we learned anything from it; but we did not. Or, rather, we seem incapable of learning from the follies of nutritional history, because our responses are surprisingly constrained by the stipulations of Newton.
The logical, and genuinely salutary reaction to the boondoggle of lipstick on low-fat pigs was to conclude that we should not fixate on any one nutrient, but rather think in terms of wholesome foods in sensible combinations. After all, if we eat truly wholesome foods in genuinely sensible combinations, there is no way to get it wrong. But alas, that kind of thinking would not have been equal and opposite, and that's how we roll.
What was equal and opposite to “just cut fat”? Obviously, “just cut carbs.” We never worried much about some potentially vexing details, such as: ALL plant foods are carbohydrate sources. Equal and opposite is a clear and compelling mandate, and if it means we lump together lentils and lollipops like so much baby and bathwater, well then, so be it.
Leaving aside whether or not cutting carbs was a better or worse idea than cutting fat, we can at least give Robert Atkins his due: When he proposed it, he presumably did not have low-carb brownies in mind. But Big Food did to Atkins exactly what it did to Keys, turning his message into an opportunity to invent a whole new inventory of highly profitable junk foods.
And again, we failed to learn from history, perhaps because we are mere pawns to the tyrannies of physics. Perhaps we are incapable of a reaction other than equal and opposite. If just cut carbs did not make us all lean and vital, let's just cut fructose. Or gluten. Or GMOs. Or grains. Or … well, we'll think of something.
Not long ago, I was beginning to grow hopeful that we had run out of ways to eat badly and might actually have to consider eating well. Eating well is not about fat or carbs, it is about wholesome foods in sensible combinations. Get the dietary pattern right, and the nutrients reliably sort themselves out. Fixate on any given nutrient, whatever the arguments for its primacy, and history dishes out nothing but precautionary tales. I had begun to hope we were out of ways to miss the forest through the trees.
But now, I am sadly less sure. The Internet greets me each day with a new barrage of angry tweets. Ideology routinely trumps epidemiology. Far from achieving separation of church and plate, the divergent convictions about diet and health grow ever more zealous, ever more vitriolic, and ever more fanatically sure. The prevailing reaction of each to all others is entirely of the equal and opposite variety.
Science, however, advances incrementally. Rarely is there cause to throw all we thought we knew yesterday under the bus and start anew. Progress is far more probable when we consider the provocations of good, new questions in the context of established answers.
Is it a good idea to cut dietary fat? We now know the question to be bad, and bad questions invite no good answers. A diet will certainly not be improved if it cuts out nuts, seeds, avocado and fish and replaces any of these with Snackwells. Is it a good idea to cut carbs? The question is equally silly. Fewer carbs could mean less refined starch and added sugar, or the renunciation of fruits and beans. Is it a good idea to vilify fructose? Not if it gives Big Food recourse to a halo for their lateral moves.
As for those tweets, they can be painful. Many are ad hominem attacks, and each of them reverberates in its own insular echo chamber. Some are so absurd that people who actually know me and my values don't know whether to laugh or cry. I generally do neither, recognizing that the unintended consequence of our New Age connections is to give every fringe and faction the same megaphone. Those propounding despicable racial slurs against the duly elected President of the United States are, presumably, a population rounding error and a lamentable, lunatic fringe, but in the Twitterverse, they are regrettably audible just the same.
That, then, is the modern challenge to public health nutrition. If every equally misguided and oppositely directed reaction to every prior, wayward action echoes endlessly in cyberspace, do we ever navigate past the din and the discord and advance beyond the follies of history? Or will we have constrained the human mind to the confinement of 140 characters, subjugated human will to the dictates of physics, and exaggerated the purview of Sir Isaac, as we tweet, and retweet, the redundancies of our doom?
David L. Katz, MD, FACP, MPH, FACPM, is an internationally renowned authority on nutrition, weight management, and the prevention of chronic disease, and an internationally recognized leader in integrative medicine and patient-centered care. He is a board certified specialist in both Internal Medicine, and Preventive Medicine/Public Health, and Associate Professor (adjunct) in Public Health Practice at the Yale University School of Medicine. He is the Director and founder (1998) of Yale University's Prevention Research Center; Director and founder of the Integrative Medicine Center at Griffin Hospital (2000) in Derby, Conn.; founder and president of the non-profit Turn the Tide Foundation; and formerly the Director of Medical Studies in Public Health at the Yale School of Medicine for eight years. This post originally appeared on his blog at The Huffington Post.