Exercise Helps Normal-Weight Women Maintain Weight
But study suggests that exercise alone is insufficient to maintain weight in heavier women
TUESDAY, March 23 (HealthDay News) -- Among women consuming a usual diet, about 60 minutes per day of sustained moderate-intensity physical activity is required to maintain normal weight and prevent weight gain, according to a study published in the March 24/31 issue of the Journal of the American Medical Association.
I-Min Lee, of Brigham and Women's Hospital and Harvard Medical School in Boston, and colleagues studied 34,079 healthy women (mean age, 54.2 years) between 1992 and 2007.
Compared to women who expended ≥21 metabolic hours per week, the researchers found that those who expended 7.5 to <21 hours per week or <7.5 hours per week gained more weight over three years (0.11 and 0.12 kg, respectively). They also observed an inverse dose-response relationship between activity levels and weight gain in normal-weight women, but not in overweight or obese women. During the course of the study, 4,540 women with a baseline body mass index of less than 25 successfully maintained their weight by expending a mean of 21.5 metabolic hours per week.
"These data suggest that the 2008 federal recommendation for 150 minutes per week, while clearly sufficient to lower the risks of chronic diseases, is insufficient for weight gain prevention absent caloric restriction," the authors conclude. "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."