An hour of exercise 'enough for women with normal weight'

Washington, March 28 (ANI): A new study by researchers in the US has suggested that moderate exercise helps middle-aged women avoid putting on the pounds, but only if they are already a normal weight.

Study author I-Min Lee of Brigham and Women's Hospital and Harvard Medical School in Boston, Mass, found that women who are overweight or obese do not appear to reap the same benefits in terms of weight-gain prevention.

Weight-loss programs can help people lose weight, but many people have trouble keeping it off.

The new results could help women figure out how much exercise is sufficient to keep from tipping the scales again.

"The weight creeps back on again, [and] people put on all the weight they've lost, and sometimes more," Live Science quoted Lee as saying.

The study involved more than 34,000 women in the United States, and looked at how much weight they gained over a 13-year period, from 1992 to 2007.

The women were divided into three groups: those who engaged in less than 150 minutes of moderate-level physical activity per week; those who performed 150 to 420 minutes of this type of activity per week; and those who did more than 420 minutes per week, which comes out to one hour a day. Moderate-level activities included things like brisk walking, gardening and leisurely bicycling.

On average, the women gained about 6 pounds (2.6 kilograms) during the study period. Those in the two lesser activity groups (less than 150 minutes or between 150 and 420 minutes) gained significantly more weight than those who exercised more than 420 minutes a week.

While more physical activity was associated with less weight gain, this finding only held true for "normal" weight women, those with body mass index (BMI) of 25 or less.

"Among heavier women, there was no relationship between how much [activity] a women did and what weight she gained," Lee said.

However, Lee notes that the physical activity levels included in the study were not very high, and higher levels might be more sufficient at preventing weight gain.

The results of the study are published in the March 24 issue of the Journal of the American Medical Association. (ANI)