New Evidence that Exercise is not Key to Weight Control

Physical activity has many proven health benefits, ranging from reducing the risk of heart disease, diabetes, and cancer to improving mental health and mood. People who are physically active tend to be healthier and live longer. But while physical activity burns calories, it also increases appetite, and people may compensate by eating more or by being less active the rest of the day.

Some experts have suggested that a decline in physical activity, especially in the workplace, has been a key contributor to the obesity epidemic. But research such as the new Loyola study, in which physical activity is objectively measured and participants are followed over time, has not found a meaningful relationship between weight gain and physical activity.

Previous research has found that when people are asked about their physical activity, they tend to overstate the amount they do. To provide a more objective measure, participants wore tracking devices called accelerometers on their waists for a week.

At the initial visit, Ghana participants had the lowest average weights (139 pounds for both men and women), and Americans the highest weights (202 pounds for women, 206 pounds for men). Ghanaians also were fitter than Americans. Seventy-six of Ghanaian men and 44 percent of Ghanaian women met the U.S. Surgeon General physical activity guidelines, while only 44 percent of American men and 20 percent of American women met the guidelines. The guidelines recommend doing at least two and a half hours of moderate-intensity aerobic exercise (such as brisk walking) per week.

Researchers did not find any significant relationships between the sedentary time at the initial visit and subsequent weight gain or weight loss. The only factors that were significantly associated with weight gain were weight at the initial visit, age, and gender.

ScienceDaily