Kids eat hefty number of calories while watching TV

Study results provide fodder for improving youngsters' diets

Elementary school children eat nearly 20 percent of their daily calories while watching television, researchers at the School of Medicine have found. Their study suggests that TV-time munching may be a good target for obesity prevention interventions.

Scientists have linked television viewing to childhood obesity in several epidemiological studies, but teasing out the reasons for this association has proved less straightforward. Previous studies have shown that children are affected by television advertising for (often unhealthy) foods, and research on adults suggests we tend to keep eating for longer when the TV is on. In the current study, researchers set out to learn more about the amounts and types of food that sample groups of third- and fifth-graders ate while watching television.

"Previous studies looked at groups of children and found that those who watched more TV were more likely to be obese," said Donna Matheson, PhD, research associate at the Stanford Prevention Research Center, who led the study published in the June issue of the American Journal of Clinical Nutrition. "We looked at individuals to find out what they were eating and when."

The researchers analyzed data from two studies, one involving ethnically diverse third-graders and one surveying predominantly Latino fifth-graders. The children were asked on three separate days what they had eaten during the previous 24 hours and what they had been doing during the meal or snack.

Contrary to popular opinion, children in the study did not eat more fatty or high-calorie foods in front of the TV than at other times. "It appears that it is not the type of foods they are eating while watching TV, but that kids may possibly consume more calories while watching TV than they would have consumed if they were not," said Thomas Robinson, MD, MPH, associate professor of pediatrics and of medicine at the Stanford Prevention Research Center and the senior author of the study. Robinson also directs the Center for Healthy Weight at Lucile Packard Children's Hospital.

The children ate an average of 1,620 calories per day, consuming about 16 to 18 percent of those calories in front of the television on weekdays and 26 percent on weekends. While fewer fruits and vegetables were eaten with the TV on, the children also consumed less soda and fast food than at other times.

Most surprising, though, according to Matheson, was the sheer number of calories the children ate while watching TV. "It's equivalent to the amount of foods consumed at other times, such as school lunch, that may be targeted for improving children's diets," she said.

But Matheson cautioned that more studies are needed before researchers have a clear understanding of the television-childhood obesity link. An intervention study to help children reduce their television viewing is now under way, and the results will help determine whether children actually eat more because they're watching television or if they would have eaten just as much with the tube off. Research in which scientists actually observe children's eating habits with and without the TV on is also needed, Matheson said, to cut the high error rates associated with self-reported food consumption.

Ultimately, though, efforts to reduce childhood obesity will need to focus on more than just television. As Matheson pointed out, "Kids eat what is available to them in their homes or at school."

Other Stanford collaborators on the study are Joel Killen, PhD, professor of medicine (research); statistical programmer Yun Wang; and senior statistical programmer Ann Varady, PhD.