“How should I eat?” is a question that many Americans ask daily. Almost everyone seems confused, and no wonder: Splashy new diet theories appear all the time, often countering what we took to be true just yesterday. Weight is about energy balance: how the daily intake of fuel that we metabolize aligns with our body’s needs.
“Diet” is a word that has twisted to mean something that someone invents for the fastest possible weight loss. There’s always a new one to “go on” for short-term results. But what diet means is how you get the nutrition you need throughout your life.
Before the 20th century, humans knew what to eat: Little or no junk (not much existed); animal products in moderation (far less was available); and relatively unprocessed plant foods in abundance. That’s what almost all traditional diets comprised, though there were variations on this theme that we might now call low-fat, low-carb, vegan, pescatarian, and so on.
In eras before that, it was even simpler: Humans ate everything we could find that wasn’t poisonous, and as long as we saw enough of it insufficient variety, we generally did fine.
But beginning in the 19th century and accelerating through the 20th, mass production and marketing of new foods started to dominate. Science and industry combined to find ways to create shelf-stable, nutrient-poor, high-calorie ultra-processed foods, from cheeseburgers to sodas, as well as almost anything you see in a vending machine or next to the checkout counter.
These have generated a public health crisis that requires us to relearn what every human once knew from instinct and experience.
The now-constant barrage of headlines about nutrition science can make us feel like we’re doing everything wrong. Some people respond by tuning out and continuing to eat what’s familiar.
Others jump on the bandwagon of each thrilling new diet that promises everything. Most of these deliver temporary results from severe restrictions that no one can maintain. Rapid weight loss is followed by rapid regain, creating a desperation that makes people eager for the next promise of magic.
The truth is that all good diets feature one or another balanced assemblage of wholesome, real foods—mostly plants. Even now, with our instincts suppressed, we know what a proper diet is. Highly processed foods, especially meats and added sugar and salt, are all significant contributors to heart disease and other chronic killers.
So how to assess the daily barrage of diet news? First, we need some perspective on nutritional research. New findings don’t usually reverse what we knew before; they add context, bit by bit. Second, we should stop obsessing about particular nutrients—such as whether fat is “good” or not.
The short answer is that unsaturated fats from nuts, seeds, fruits, and fish tend to be beneficial. In contrast, saturated fats, commonly found in meat and dairy and far too widely consumed, tend to be detrimental. Fiber and added sugars are simpler, to sum up—in our new habits we badly need more of the former and less of the latter.
But the best approach is to focus on real foods rather than to fixate on their components. From a food-by-food vantage point, some principles emerge that will outlast all diet fads.
Live your life, Love your life
Hippocrates was to thank for the famous quote, “Let food be thy medicine and medicine be thy food” — which we translated to “food is medicine” and use as our motto. Still to this day medical doctors and historians consider Hippocrates to be the founder of medicine as a “rational science.”