Study Finds that Both Weight and Exercise Are Key to Longevity
For immediate release: December 22, 2004
Boston, MA— New research findings from the Department of Nutrition at the Harvard School of Public Health and Brigham and Women’s Hospital show that increased body fatness measured by body-mass index (BMI) and reduced physical activity are both strong and independent predictors of premature death in women. The study appears in the December 23, 2004 issue of the New England Journal of Medicine.
Body-mass index is determined by dividing an individuals’ weight in kilograms by the square of height in meters. For non-metric, weight in pounds is divided by the square of height in inches, then multiplied by 703. A BMI over 25 is considered overweight. Approximately two thirds of Americans are classified as overweight or obese.
More than 115,000 participants who were free of cardiovascular disease or cancer, 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. In the questionnaires the women were asked to report on average how much time was spent per week on moderate physical activities such as brisk walking, and vigorous physical activities, among them, jogging, running, bicycling, playing tennis and swimming laps. 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 half-fold increase in risk of death for inactive and obese women. The researchers estimated that excess weight (BMI over 25) and physical inactivity (less than 3.5 hours per week) 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. During the 24 year span of the study, 10,282 deaths occurred; 2,370 from cardiovascular disease, 5,223 from cancer and 2,689 from other causes.
“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. “There is no question that one should be as active as possible no matter what your weight is, but it is equally important to maintain a healthy weight and prevent weight gain through diet and lifestyle.”
Funding for the study was provided by grants from the National Institutes of Health.
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