The more exercise, the better: That’s the message a group of researchers is delivering to postmenopausal women.

The researchers from Canada said the women in their study who did 300 minutes (5 hours) of exercise a week showed definitive decreases in body fat and weight compared to other postmenopausal women who did 150 minutes (2.5 hours) of exercise a week.

Women tend to gain weight and body fat after menopause, which increases their risk for breast, kidney, and other cancers.

“There was definitely more benefit for the women who exercised more. It was definitely worth the extra effort,” said Christine M. Friedenreich, Ph.D., of Alberta Health Services, in an interview with Healthline.

The study was published today in JAMA Oncology a publication of the American Medical Association.

400 Women, 52 Weeks

The researchers studied 400 inactive postmenopausal women in their experiment. Their body mass indexes (BMIs) ranged from the upper half of healthy weight to morbidly obese.

Half of the women were told to exercise 150 minutes a week. That regimen reflects the guidelines issued by global public health agencies for cancer prevention. The other half were told to exercise twice as much, or 300 minutes a week.

Older Woman Exercise

Both groups exercised five days a week, walking, running, bicycling, or using an elliptical trainer. Strength training was not involved.

The women were asked not to change their diet. The exercise routine lasted for one year.

Losses in Weight, Body Fat

It was no surprise that the women who exercised more lost more weight and body fat. The surprise was how much more.

The 300-minute group lost on average 1 percent more of their body fat than the 150-minute group. They also had larger reductions in their subcutaneous abdominal fat, total abdominal fat, waist circumference, and waist-to-hip ratio. 

The results were more dramatic for women who were listed as obese at the start of the exercise program.

Friedenreich said the results of the study should encourage doctors to recommend 300 minutes a week of exercise for postmenopausal women, instead of the standard 150 minutes a week for cancer prevention.