As you get older, your body changes how it gains and loses weight. Both men and women experience a declining metabolic rate, or the number of calories the body needs to function normally. On top of that, women have to deal with menopause. "If women gain weight after menopause, it's more likely to be in their bellies," says Michael Jensen, MD, professor of medicine in the Mayo Clinic's endocrinology division. In menopause, production of the hormones estrogen and progesterone slows down. Meanwhile, testosterone levels also start to drop, but at a slower rate. This shift in hormones causes women to hold onto weight in their bellies. The good news: you can fight this process. Read on.