Over 115,000 participants who were free of cardiovascular disease or cancer, who were between the ages of 30 and 55 and had filled out biennial health and lifestyle questionnaires between 1976 and 2000, were chosen for the study from the Brigham and Women’s Hospital-based Nurses’ Health Study. The women answered questionnaires that asked on average how much time was spent per week on moderate physical activities and vigorous physical activities. Women who spent 3.5 hours per week or more exercising were considered physically active. The researchers found that both obesity and physical activity significantly and independently affected mortality. A high level of physical activity did not eliminate the risk of premature death associated with obesity and leanness did not counteract the increased risk in mortality conferred by inactivity. Compared to physically active, lean women, there was nearly a two-and-a-half- fold increase in risk of death for inactive and obese women. The researchers estimated that excess weight (BMI over 25) and physical inactivity accounted for 31 percent of all premature deaths among the study participants with 59 percent of the deaths attributable to cardiovascular disease and 21 percent from cancer among the non-smoking women. “It is clear that both weight and exercise are important for health and longevity,” said Frank Hu, lead author of the study and an associate professor of nutrition and epidemiology at the Harvard School of Public Health.