June 29, 2010 --There is evidence that a little bike riding could help premenopausal women stay slim. The study in the Archives of Internal Medicine finds riding a bike is as effective as walking briskly at helping premenopausal women keep from gaining weight. Experts say this is specifically true for overweight and obese women. They found bicycling just 2-to-3 hours per week makes them 46 percent less likely to gain more than 5 percent of the initial body weight over the long run. Researchers also found slow walking does not help control weight.