MIAMI, March 8 – Eating fast food and watching TV add up to a high risk for obesity and diabetes, according to a study reported today at the American Heart Association's 43rd Annual Conference on Cardiovascular Disease Epidemiology and Prevention.
"Fast food consumption in this country has increased dramatically," says Mark Pereira, Ph.D., assistant professor of pediatrics at Harvard Medical School and Children's Hospital in Boston. "The association between eating fast food and the incidence of obesity and abnormal glucose control has not been thoroughly examined before."
Researchers found that eating fast food meals more than twice a week was associated with double the risk of abnormal glucose control and a 50 percent increase in the risk of obesity.
In personal interviews, the researchers also asked study participants about their television viewing habits. They found that among white adults, frequent fast food meals and hours spent watching TV combined to increase the odds of obesity and abnormal glucose metabolism. Whites who watched TV more than three hours a week and ate fast food more than twice a week were three times as likely to have abnormal glucose metabolism than those who watched less than an hour of TV per week or ate fast food less than once a week.
The study followed 2,027 white and 1,726 black adults between ages 18 and 30 for 15 years. Study participants were interviewed about their dietary habits and lifestyle and given physical examinations. Participants were considered obese if their body mass index (BMI) was 30 or greater, or their waist girth was greater than 39 inches for men or 35 inches for women. BMI is a person's weight in kilograms, divided by height in meters squared. Abnormal glucose control was identified by a fasting glucose of at least 110 milligrams per deciliter and fasting insulin of 20 microunits per milliliter. Both obesity and abnormal glucose control are strong risk factors for heart disease and type 2 diabetes.
After adjustments for demographic factors, smoking, alcohol use and physical activity, fast food frequency was directly associated with the risk of developing obesity and abnormal glucose metabolism in whites but not in blacks.
Pereira says the lack of a strong association in blacks may be due to underlying dietary patterns or that the interviews may not have adequately assessed the dietary habits among blacks. The risk association in blacks will require further study, he adds.
One of the mechanisms of increasing the risk of obesity and glucose metabolism is the overall affect on dietary quality, he says. "When you eat fast foods, you eat fewer fresh fruits and vegetables, fewer whole grains, and fewer reduced-fat dairy products and fiber.
"Both eating fast food and watching television were independent risk factors. Many individuals were eating at fast food places more than three times per week. The actual meal didn't seem to matter – hamburgers, fries, breakfast sandwiches, chicken sandwiches and nuggets – they were all associated with an increased risk."
Pereira says that Americans may be susceptible to television advertising of fast foods, but most people probably don't realize the long-term effects on their lifestyle and health.
"There are a quarter of a million fast food restaurants in this country. Further study of fast food on public health should be given a priority."
All Americans need to reduce the number of fast food meals to help avoid the growing epidemic of obesity and diabetes in this country, he says. "Try to get in the habit of picking up your food in grocery stores instead of the fast food window; and eat at home with family and friends if possible."
Co-authors are Alex I. Kartashov, Ph.D.; Cara B. Ebbeling, Ph.D.; Joan E. Hilner, M.P.H., R.D.; Linda Van Horn, Ph.D., R.D.; Martha L. Slattery, Ph.D., R.D.; David R. Jacobs Jr., Ph.D.; and David S. Ludwig, M.D., Ph.D.
Materials provided by American Heart Association. Note: Content may be edited for style and length.
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