OK, OK, so just about everyone knows your metabolism begins to drop—and your dress size starts to go up—once you hit your 30s. But what you may not know is that it doesn’t have to. The main reason your body starts to pack on the pounds isn’t because you’re aging and your metabolism is slowing—it’s because you’re exercising less (or just not enough).
So what’s the harm in taking a break from your workouts and letting your belt out a couple of notches? That weight gain and muscle loss can really snowball over the years, says JoAnn Manson, MD, chief of preventive medicine at Harvard’s Brigham and Women’s Hospital, leading to an added 20 to 30 pounds by the end of your 50s, not to mention brittle bones and increased risks of heart disease and type 2 diabetes.