Women who are middle-aged or older who currently fall in the normal range on the body mass index (BMI) need at least an hour a day of moderately intense exercise to maintain their weight, according to findings published in the latest issue of the Journal of the American Medical Association.
The study, led by Dr. I-Min Lee of Brigham and Women’s Hospital’s (BWH) Division of Preventive Medicine, collected and analyzed data from over 34,000 American women described as healthy. The women would report their leisure-time activity every two to three years over a 13 year period.
The study grouped the female participants into three groups based on the amount of exercise they completed per week. The most active women engaged in the equivalent of at least 420 minutes per week of moderately intense physical activity (such as brisk walking) — the amount recommended by the Institute of Medicine in 2002. The middle group exercised for between 150 and 420 minutes, and the third group completed minimum 150 minutes recommended by 2008 federal guidelines.
According to a March 22 BWH press release discussing the findings, “Over the duration of the 13-year study, the average weight of participants increased by 6 pounds, which is a rate of weight gain similar to that of comparably aged women in the general population. Compared to the most active women (i.e., the 420 min/week, or 60 min/day, or more group), both the group physically active for 150 to less than 420 min/week, and the group physically active for less than 150 min/week, gained significantly more weight than the most active group. The two less active groups also were significantly more likely to gain at least 5 pounds, compared to the most active group.”
The research team also found that the results varied by BMI rating, and that the correlation between physical activity and reduced weight gain was only applicable to those in the normal BMI range.
“There is plenty of research on treating overweight and obesity — that is, looking at strategies for weight loss among overweight or obese persons, but very little research on preventing weight gain in the first place,” Lee said in the BWH press release. “Most overweight and obese persons who lose weight do not successfully maintain their weight loss over time, and so from a public health prospective, preventing that initial weight gain is important.”
However, she is quick to add that the findings “shouldn’t obscure the fact that for health, any physical activity is good, and more is better. It is important to remember that weight is only one aspect of health. Many studies have shown that being physically active for even 30 minutes a day, 5 days a week, significantly reduces the risk of developing many chronic diseases such as cardiovascular disease, some cancers, and type 2 diabetes.”
—
On the Net:
Comments