Women may need to surpass federal guidelines on physical activity to keep the pounds off as the years progress. Those who successfully maintained normal weight and gained fewer than 2.3 kg (5.07 lbs) over 13 years averaged approximately 60 minutes per day of moderate-intensity exercise throughout that time period—almost three times the weekly recommendation set forth by the 2008 Physical Activity Guidelines for Americans.

In a prospective study of 34,079 healthy U.S. females (mean age: 54 years) taking part in the Women’s Health Study, there was an overall weight gain over the 13-year study period, as expected, but normal-weight women who engaged in the equivalent of 420 minutes per week (60 minutes per day) of moderate-intensity physical activity such as walking, hiking, jogging, or biking gained significantly less weight than less active women. The less active women were also significantly more likely to gain at least 5 lbs over a three-year period than the most active women.

“These data suggest that the 2008 federal recommendations for 150 minutes per week [of moderate-intensity physical activity], while clearly sufficient to lower the risks of chronic diseases, is insufficient for weight gain prevention absent calorie restriction,” observed the authors. (JAMA. 2010;303:1173-1179).