Dr. I-Min Lee from Brigham and Women's Hospital in Boston and co-authors studied more than 34 thousand women starting at an average age of 54, following and updating their activity level for 13 years. The women were divided into three groups: those exercising 60, 30 and less than 30 minutes daily.
They found that middle-aged and older women, at a normal weight, who ate a regular diet , needed an hour of daily exercise just to maintain their weight
Dr. Lee elaborated, "if you want to prevent your weight gain over time, you need to be physically active at the level of 60 minutes of moderate intensity physical activity , so the equivalent of one hour a day of brisk walking or 30 minute s a day of jogging or running."
An hour of exercise every day didn't keep overweight or obese women from gaining weight over time.
Researchers say it's important to keep in mind that regular physical activity helps lower your risk of developing chronic diseases, such as heart problems and diabetes, even if it doesn't keep the weight off.