Turn Off Tube To Prevent Obesity, Diabetes

Obesity rates have jumped in past years ... and so has the amount of time spent watching TV.

Harvard rsearchers found that limiting TV time and adopting a more active lifestyle could go a long way toward preventing obesity and type 2 diabetes.

The study is published in Wednesday's issue of the Journal of the American Medical Association.

According to a survey conducted in the United States in 1997, an adult male spent about 29 hours per week watching TV and an adult female spent 34 hours per week watching TV. Compared with other sedentary activities -- including sewing, playing board games, reading, writing and driving a car -- TV watching results in a lower metabolic rate, the report said.

Prolonged TV watching is also linked to obesity in children. Current public health campaigns to reduce obesity and type 2 diabetes have largely focused on increasing exercise, but have paid little attention to reducing sedentary behaviors, according to the article.

Dr. Frank Hu and his team from Harvard School of Public Health and Brigham and Women's Hospital in Boston studied data on 50,277 women who participated in the Nurses' Health Study, which was conducted from 1992 to 1998 among women from 11 states. This study included women with body mass indexes of less than 30 (a BMI of 30 or higher indicates obesity; a 5-foot, 4-inch woman would have a BMI of 30 if she weighed 174 lbs.) Calculate your BMI.

Over the six years of follow-up, researchers found that time spent watching TV was positively associated with risk of obesity and type 2 diabetes.

After adjusting for age, smoking, exercise levels, and diet, the researchers found that each two-hour daily increment of TV-watching was associated with a 23 percent increased risk of obesity and a 14 percent increase in the risk for diabetes. Each additional two hours per day increment of sitting at work or driving was associated with a 5 percent increased risk of obesity and a 7 percent increased risk of diabetes.

However, standing or walking around at home for two hours a day was associated with a 9 percent reduced risk of obesity and a 12 percent reduced risk of diabetes. Each hour per day of brisk walking reduced obesity risk by 24 percent and diabetes risk by 34 percent.

The researchers estimated that 30 percent of new cases of obesity and 43 percent of new cases of diabetes could have been prevented by adopting a relatively active lifestyle of less than 10 hours per week of TV-watching and 30 minutes or more per day of brisk walking.

The researchers said TV-watching may increase the risk for obesity and diabetes in three ways:

TV-watching typically displaces physical activity and reduces the amount of time used to burn energy, the researchers wrote.
People tend to eat while watching TV despite their low physical activity levels, resulting in increased food and total energy intake.
"Also, participants who spent more time watching TV tended to follow an unhealthy eating pattern," the researchers wrote. "Such an eating pattern is directly related to commercial advertisements and food cues appearing on TV and has been associated with risk of obesity and diabetes."
TV-watching burns less energy compared to other sedentary activities like sewing, reading, writing, and driving a car, the reserachers wrote.

Other Obesity Studies From This Week's JAMA:

Overweight Kids Report Low Quality Of Life
Long-Term Safety Of Low-Carb Diets Unknown
Medication Helps Overweight Teens Shed Pounds
Study: Online Weight-Loss Program Successful