Turns out that calories might not be the main reason for obesity. In a new study, researchers from Loyola University Health System compared Black Chicago women to women in rural Nigeria. What they found was that, on average, the Chicago women weighed 184 pounds to Nigerian women’s 127 pounds. What the researchers expected to find was that the Nigerian women were more physically active. Not so. In fact, what they discovered is that there is no significant difference between the two groups in the amount of calories burned during physical activity. “Decreased physical activity may not be the primary driver of the obesity epidemic,” said Loyola nutritionist Amy Luke, an associate professor in the Department of Preventive Medicine and Epidemiology. U.S. government guidelines call for at least 2 ½ hours of moderate aerobic activity (such as brisk walking) or 75 minutes of vigorous activity (such as jogging) each week. Adults also should do muscle-strengthening activities, such as weight-lifting or sit-ups, at least twice a week. Such activity not only strengthens bones and muscles, but it improves mental health and mood, lowers blood pressure, improves cholesterol levels and reduces the risk of cardiovascular disease, diabetes, breast cancer and colon cancer. But Luke and her cohorts found that weight control might not be among the main benefits. Although people definitely burn more calories when they exercise, they compensate by eating more, says Richard Cooper, Ph.D., co-author of the study and chairman of the Department of Preventive Medicine and Epidemiology. “We would love to say that physical activity has a positive effect on weight control, but that does not appear to be the case,” Cooper said.