CORVALLIS, Ore. – A national team of researchers from the American College of Sports Medicine has examined the evidence regarding physical exercise guidelines for weight maintenance and concluded that greater amounts of physical activity are needed – and modest weight losses can have significant health benefits.
The study, published in the February issue of Medicine & Science in Sports & Exercise (the flagship journal of the American College of Sports Medicine), updates a 2001 position stand by the ACSM.
The new study argues that increased levels of physical activity may be needed for prevention of weight gain and for weight loss. In a country where now more than 66 percent of people are clinically defined as overweight or obese, a reduction in obesity is now a national public health initiative.
Melinda Manore, a professor and extension specialist in the Department of Nutrition & Exercise Sciences at Oregon State University, is one of the co-authors of the study. Manore said their research found that a minimum of 150 minutes of moderate-intensity physical activity per week is needed just to maintain current weight levels and greater amounts of exercise are needed to lose significant amounts of weight. This number for maintenance of weight is higher than some previous recommendations, which ranged from 35 minutes to 80 minutes of moderate to high-intensity activity per week, depending on the study.
“Most people gradually gain weight, about one to two pounds a year, over their adult life,” Manore said. “This is why exercise is so crucial in the prevention of weight gain. In terms of the obesity epidemic in the country, we now feel we might be successful if we can just get people to stop gaining weight.”
Manore said research suggests that significant weight loss can be obtained with a combination of moderate diet restriction and a more expansive exercise regime that includes more than 250 minutes of exercise per week. Manore said moderate intensity exercise, such as a brisk walk, rather than high-intensity cardio is what was tested on most participants.
Another significant change from the 2001 position paper emerged. Manore said researchers previously held to the understanding that a 10 percent reduction in weight would lower health risks. Now, she said the data shows that as little as 3-5 percent loss of weight could yield significant changes in critical area such as high blood pressure, improved glucose tolerance and blood lipids, and other factors that contribute to improvement in health.
Manore pointed to a recent longitudinal study that followed 2,755 women for 15 years. The women were 18-30 years of age when they started the study. Those women who walked 30 minutes a day were compared to those with no leisure time walking. After 15 years, the group of women who exercised had gained 16 fewer pounds than the non-walking group.
“We need to start thinking about weight gain and loss in different terms,” Manore said. “It doesn’t mean thinking exercising or eating better for finite periods for a specific weight goal. It needs to be a lifestyle change that incorporates healthy eating and physical activity into your everyday life.”
The lead author is Joseph E. Donnelly of the University of Kansas. Other contributors to the article are Steven N. Blair of the University of South Carolina, John M. Jakicic of the University of Pittsburgh, Janet Rankin of Virginia Tech, and Bryan K. Smith of the University of Kansas.
A copy of the study is at: http://oregonstate.edu/dept/ncs/photos/weightstudy.pdf