CAMBRIDGE, MA – The maxim “you are what you eat” has defined dietary thinking for hundreds of years. The prevailing interpretation is simple: our bodies, like the foods that we eat, are chemical compositions. In order to live long and healthy lives, and to maximize our potential, we must consume the right chemicals – that is, foods with the right nutrients. Not so long ago, however, this saying was understood quite differently, indicating a profound shift in the way that we think about our diet and ourselves – a shift that has powerful implications for current health debates.
In ancient Greek and Roman medicine, prevention was key. Regimen, commonly called dietetics, prescribed a lifestyle designed to keep people healthy. Indeed, while doctors did everything in their power to cure ailing patients, dietetics was considered the most important area of medical practice. After all, with a sound diet, one would presumably never need a cure.
Dietetics was a prescription for an ordered manner of living, guiding people not only on matters of food and drink, but on all governable aspects of their lives that affected well-being, including their places of residence, exercise, sleeping patterns, bowel movements, sexual activity, and an area neglected by medicine today: emotional control.
In short, dietetics was a matter of virtue as well as of bodily health. The medical profession doled out advice about how one should eat in the same breath as instructions about how one should live – and about what sort of person one should be.
Traditional dietetic advice now seems banal, with its almost exclusive focus on moderation. For example, dietetic counsel would recommend that patients eat neither too much nor too little; sleep when necessary, but not excessively; exercise, but not violently; and control anger and stress. The Temple of Apollo at Delphi bore the inscription, “Nothing in excess,” while Aristotelian philosophy held that the golden mean was the path to the good.
Given the current frenzy of fad diets and the eternal search for simple remedies for complex conditions, moderation in all things may seem like shabby medicine. But dietetics’ conviction that health and morality are two sides of the same coin is a deep-rooted notion. After all, Christianity lists gluttony as one of the seven deadly sins, while temperance is one of the cardinal virtues.
Both good and good for you, moderation became a commanding idea: by rooting medical advice in powerful systems of social values, dietetics shaped medical thought for centuries. Rejecting dietetic advice amounted to rejecting moral wisdom.
This merging of medicine and morality now seems naively unscientific, thanks to “nutrition science,” which replaced traditional dietetics as a formal discipline in the nineteenth and twentieth centuries. Nutritional experts today are more likely to suggest monitoring cholesterol levels than they are to give such holistic and common-sense advice as moderation. Gluttony was once a sin; obesity is now a disease (or a “risk factor” for other diseases).
Because science ostensibly advances by setting aside moral questions to address material cause-and-effect relationships, this shift could be perceived as progress. But the separation of the “good” from the “good for you” limits the influence of modern nutritional expertise on people’s behavior, ultimately undermining the goal of improving public health......