Press Releases

2003 Releases

Women Who Reduce Sedentary Behaviors Significantly Reduce Risk for Type 2 Diabetes and Obesity

For immediate release:  April 08, 2003

Boston, MA— A new study from the Harvard School of Public Health finds that women who avoid sedentary behaviors such as watching television more than ten hours per week and incorporate a thirty-minute brisk walk into their day, reduce the risk of onset of type 2 diabetes by 43 percent and obesity by 30 percent compared to women with sedentary lifestyles. The findings appear in the April 9, 2003 issue of the Journal of the American Medical Association.

Using data from the Nurses' Health Study, the researchers assessed the physical activity and sedentary behaviors of more than 68,000 women over a span of six years and the relationship to onset of type 2 diabetes and obesity. At the start of the study the women completed a questionnaire about physical activity and sedentary behaviors, follow-up questionnaires were sent every two years. Participants had to be free of diabetes, heart disease, cancer and have a body mass index (BMI) of 30 or under. BMI is calculated by dividing a persons weight, in kilograms, by height in meters squared. A person with a BMI between 25 and 29.9 is considered overweight. Individuals who fall into the BMI of 30 or greater are considered to be obese. Follow-up.

During the six years of follow-up, more than 3700 women who had a BMI less than 30 at the start of the study became obese and more than 1500 new cases of type 2 diabetes were diagnosed.  The researchers found that compared with women who spent less than two hours per week watching TV, those who spent at least three hours per day watching TV had a 40% increased risk of obesity and a 30% increased risk of type 2 diabetes. Those who spent at least five hours per day watching TV had a two-fold increased risk of obesity and 70% increased risk of diabetes.  Other sedentary behaviors such as sitting at work or at home were also associated with increased risk of obesity and diabetes. In contrast, standing or walking around at home two hours per day was associated with a nine percent reduction in risk of obesity and 12 percent for diabetes. Each hour per day of brisk walking was associated with a 24 percent reduction in risk for obesity and a 34 percent reduction of risk for diabetes.

Lead author of the study and Associate Professor of Nutrition and Epidemiology at the Harvard School of Public Health, Frank Hu said, “The message is simple, when you cut back on sedentary behavior, you cut back on the risk of developing type 2 diabetes and obesity which lead to serious health risks. Excessive time in front of the TV has been shown to contribute toward bad eating habits, such as eating foods high in saturated fats and increased caloric consumption. Incorporating more physical activity shows the greatest protection against obesity and diabetes; brisk walking, even doing chores around the yard and house can help.”

The study was supported by grants from the National Institutes for Health.

For further information, please contact:

Robin Herman
Office of Communications
Harvard School of Public Health
677 Huntington Avenue
Boston, MA 02115
Phone: 617-432-4752
Email: rherman@hsph.harvard.edu