If youre not overweight and want to stay that way, you may need to exercise even more than the 150 minutes per week that federal guide-lines recommend. And if youre already overweight, it may be too late for exer-cise to get you slim-although physical activity can still have important benefits against chronic disease. Those were the depressing findings of a new analysis of data on 34,079 healthy US women, average age 54, from the Womens Health Study.Over an average follow-up of 13 years, the women gained an average of nearly six pounds. The 13.3% of women who managed to gain less averaged 60 minutes dai-ly-420 minutes a week-of moder-ate physical activ-ity, such as brisk walking (or half as much intense exercise, such as jogging). Physi-cal activity was associated with reduced weight gain, but only among normal-weight women; for those with a body-mass index (BMI) of 25 and up, exercise had no effect on weight control. The women maintained a usual diet, suggesting that if you cant carve out an hour for activity daily, the only way to keep the pounds off is restricting calories.TO LEARN MORE: JAMA, March 24/31, 2010; abstract at jama.ama-assn.org/cgi/content/abstract/ 303/12/1173
