Professor in the Department of Nutrition, Harvard T.H. chan School of Public Health and author of Always Hungry? Conquer Cravings, Retrain Your Fat Cells & Lose Weight Permanently
Q: What is the ideal New Year’s resolution for losing weight?
A: Forget calories, focus on food quality, and let your body do the rest.
Cutting back on calories, the time-honored approach to weight loss, will work for the short term. But for most people, it eventually fails, for a simple reason: The body fights back in predictable ways against enforced calorie deprivation—through rising hunger, slowing metabolic rate, and production of stress hormones. Only a vanishingly small fraction of people can keep weight off through calorie restriction. That’s not because of poor willpower—it’s because of biology.
The main problem with our diet today is that it has been hyperprocessed. It is fast food in every sense of the word: You eat it quickly, but you also digest it quickly, causing a surge and crash in metabolism. Processed carbohydrates program our bodies for weight gain, because they raise levels of the hormone insulin, which is like Miracle-Gro for fat cells. Natural, whole foods, on the other hand, are digested across the full length of the intestinal tract, which leads to a gentle rise of blood sugar and a gentle return to baseline. Calories are not shunted into storage in fat tissue, but rather used—oxidized, in biological terms—by the rest of the body and the brain.
To gain these benefits, do three things: First, replace processed carbs with whole fruits, vegetables, legumes, and modest amounts of whole-kernel grains. Second, eat an adequate amount of protein, which can include plant sources. Third, enjoy plenty of delicious high-fat foods—nuts, nut butters, olive oil, and even full-fat dairy, rich sauces and spreads—because fat is filling and has minimal effect on insulin. When you eat this way, blood sugar, hormones, and insulin change more gradually after the meal. It’s like an ocean tide that gently rolls in and rolls out, versus a tsunami—a natural process of feeding and fasting that the body adapts to easily. Fat cells calm down and store less. Hunger decreases. Metabolism speeds up. It’s a recipe for long-term weight control without restriction or deprivation.
Any weight-loss approach that involves deprivation wears you down, psychologically and biologically. But if you give your body what it needs, it gives you immediate positive feedback, and that’s reinforcing. The beauty of working with, rather than against, your body is that your New Year’s resolution never expires.