This reminds me of taxes. We're all getting used to the health police telling us we need to exercise 3 x a week, and then they up the ante.
"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 minutes a day of jogging or running," said I-Min Lee, M.B.B.S., Sc.D., of Brigham and Women's Hospital in Boston.
Dr. Lee and co-authors studied more than 34,000 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. "These two lesser activity groups of women were significantly more likely to gain weight compared to the most active group of women," said Lee.
The study appears in this week's JAMA, Journal of the American Medical Association. "We found that physical activity was effective in controlling weight only among women who started off with a normal BMI," said Lee. "The women who were overweight or obese, physical activity, with the range done in the study was not sufficient to control their weight."
For heavier women, researchers say not to let the 60 minutes of daily exercise discourage you from starting or continuing to exercise. "While our study shows that this might not be sufficient to maintain normal weight it clearly is sufficient to reduce the risk of developing many chronic diseases including heart disease, certain types of cancer, type II diabetes," said Lee.
Researchers report that women in the study consumed a regular American diet and did not restrict their calories."