60 minutes of moderate exercise can keep your scales happy, says research

By Dr. Ananya Mandal, MDMar 24 2010

More moderate activity per day

With age most women consuming a normal diet may tend to gain weight. New reports however suggest that a mere 60 minutes exercise per day can keep middle aged weight gain in women at bay.

Current federal guidelines suggest 150 minutes per week or 30 minutes five days a week of moderate to intense exercise to lose weight. These new findings show that more time with moderate activity is needed. Activities like walking, leisurely bike rides or playing catch may be enough as moderate activities. Running, jogging, fast cycling and swimming count as intense activity wherein only 30 minutes a day may be enough.

This report comes from a published study in the Journal of the American Medical Association March 24/31 issue.

"I don't want people to throw up their hands and say 'I can't do it,' " said I. Min Lee, the study's lead researcher, doctor and associate professor at Harvard Medical School and Brigham and Women's Hospital in Boston.

The Study

A study was undertaken as a part of the Women's Health Study. In 2002 the Institute of Medicine suggested 60 minutes a day, or 420 minutes a week for prevention of weight gain. As this was more than the federal recommendations a closer look was needed says Dr. Lee.

This study had 34,079 participants who were healthy U.S. women aged 45 and above on normal diet from 1992 to 2007. They were asked to fill in questionnaires at the commencement and at 3 year intervals regarding activity and exercise per week and their weight changes were tracked on three yearly basis for 13 years.

Overall the women gained an average of 5.7 pounds. But those with normal weight and body mass index of less than 25 maintained their initial weight only if they exercised 60 minutes a day. Initially from the results the association of physical activity and weight control seemed universal. But over the years the results came out different Lee says.

"These data suggest that the 2008 federal recommendation for 150 minutes per week, while clearly sufficient to lower the risks of chronic diseases, is insufficient for weight gain prevention absent caloric restriction," wrote Dr. Lee.

Expert speak

According to Suzanne Phelan, PhD, assistant professor of kinesiology at California Polytechnic State University in San Luis Obispo and adjunct assistant professor of research at Brown Medical School in Providence, R.I., who has researched the topic.

"To keep a normal body weight is hard work," she says. As you age, she says, "you have to exercise a lot whether you are normal weight or maintaining a weight loss." She says 10 minute bouts of moderate activity can be a solution if 30 or 60 minutes seem too long.

Peter Galier, MD, a staff physician at Santa Monica-UCLA & Orthopaedic Hospital in California and an associate professor of medicine at the University of California, David Geffen School of Medicine says,

''As you get older, your basal metabolic rate [calories burned at rest] goes down," he says. Thus he emphasizes the need to exercise regularly to keep the same weight.