Exercise and Age-Related Weight Gain

Approximately one third of the U.S. adult population is overweight. The Year 2000 Objectives call for reducing the prevalence of overweight to 20 percent; thus weight control has become an important public health goal.

The most commonly reported method of weight loss is dieting. However, the long-term success rate of this method is quite poor. Indeed, only about ten to 30 percent of those who lose weight by reducing calories maintain their full weight loss over time.

A study just published in the International Journal of Obesity reports some encouraging findings with regard to the benefits of physical activity to weight control. In a large survey of over 5,000 middle-aged men and women, Loretta DiPietro, Ph.D., M.P.H. and colleagues compared two-year improvements in cardiorespiratory fitness (determined by performance on a maximal exercise test on a treadmill) with changes in body weight over seven and a half years. Each one-minute improvement in treadmill time significantly minimized weight gain by about .60 kilograms (1.3 pounds) over the follow-up period compared to participants who demonstrated no improvement.

More substantial improvements of three and five minutes were related to actual weight loss in both men and women. Further, each one-minute improvement in treadmill time reduced the chance of a five-kg (11 pounds) weight gain by 14 percent in men and by nine percent in women and the chance of a ten-kg (22 pounds) gain by 21 percent in both men and women.

These results were not due to chance or other factors associated with exercise and body weight, such as smoking. It should be noted, however, that improvements in fitness level were necessary to minimize weight gain; simply maintaining a given fitness level was not sufficient to ward off the slow increase in body weight through middle age. Indeed, these and other recent findings by Paul T. Williams, Ph.D. in The American Journal of Clinical Nutrition, suggest that increasing amounts of physical activity may be necessary to effectively maintain a constant body weight with increasing age.

"Reprinted with permission of the American College of Sports Medicine, "Alcohol and Athletic Performance," April 2000 www.acsm.org.