“Diets don’t work because they require us to live in a constant state of war with our bodies. “Whenever you restrict food intake, you’re going to run up against your own biology,” explains Dr. Sharma. “It doesn’t matter what program you follow. As soon as your body senses that there are fewer calories going in than going out, it harnesses a whole array of defense mechanisms to fight that.” When we’re dieting, our bodies try to conserve energy, so our metabolism slows down, the result being that you have to eat even less to keep losing weight. That becomes an increasingly difficult project because our bodies also produce more of the hormones, such as ghrelin, that trigger hunger. There is even some evidence that the bacteria in our guts respond when we eat fewer calories, shifting their populations in ways that will send more hunger signals to our brains.”