Exercise Now, Prevent Weight Gain Later

Women who consume a normal diet can prevent weight gain over the years by doing moderate exercise for up to 60 minutes a day.
Researchers examined weight changes in women associated with different levels of physical activity over a period of 15 years (1992 - 2007). The study include 34,079 women who consumed usual diets, and the women were broken into groups of activity levels; 7.5, 7.5 to less than 21, and 21 or more hours of activity per week.
On average, the women gained 5.7 lbs throughout the study. There was no significant difference in weight gain among the different activity groups, with those who exercised 7.5 to less than 21 hours per week gaining .2 lbs per week and those who exercised less than 7.5 hours gaining .3 lbs per week.
Results also showed a significant relationship between body mass index (BMI) and weight gain response to activity levels. Of the study participants, 13 percent of the women with BMI lower than 25 were able to successfully maintain their weight by gaining less than 5.1 lbs, but those with BMI between 25 to 29.9 or higher than 30 were unsuccessful in weight management or weight loss.
"The data suggests that the 2008 federal recommendation for 150 minutes [of activity] per week is insufficient for weight gain prevention," study author I-min Lee, M.B.B.S, Sc.D., of Brigham and Women's Hospital and Harvard Medical School, was quoted as saying. "Physical activity was inversely related to weight gain only among normal-weight women. Among heavier women, there was no relation, emphasizing the importance of controlling caloric intake for weight maintenance in this group."

SOURCE: JAMA, March 24, 2010