To Stay Thin, Exercise Beats Dieting

Sure, exercise and diet are the two pillars of maintaining a healthy weight, but which is more influential? Writing in the New York Times, Gretchen Reynolds reports on a new study that gives the nod to exercise. The study, conducted with rats, not humans, found that rats that ran during adolescence kept the weight off better, were metabolically healthier, and had different gut microbes, than rats that keep the weight off by cutting back on food. The study, by researchers at the University of Missouri, divided a group of rats into three smaller groups, one of which could eat as much as the rats wanted and kept the rats sedentary, one of which could eat as much as the rats wanted but allowed the rats to run, and one of which was given a calorie restricted diet designed to keep the animals at the same weight as the running rats. After 11 weeks, the rats were given physical exams. Yes, the sedentary eaters were obese, and the runners and dieters had gained a little weight, but none were obese. The big differences were metabolical. The runners had better insulin sensitivity and better cholesterol readings, and they burned more fat each day. They also had different gut bacteria than the dieters, even though they ate the same food. And one more thing: the runners “showed no signs of compensatory eating or compensatory inactivity.” In Gretchen Reynolds words, they seemed “better set up to avoid weight gain in the future.”