The prevalence of obesity is tied to the number of hours spent watching television, says Carlos Crespo, an epidemiologist at the State University of New York at Buffalo and the principal author of the study. At the same time, we should have a national health objective of limiting children to two hours or less of television watching a day. Crespo and researchers from Johns Hopkins University, the National Cancer Institute and the Centers for Disease Control and Prevention analyzed data from 4,069 children who took part in the third National Health and Nutrition Examination Survey, conducted by the CDC between 1988 and 1994. Crespo's group used information from this survey to study the relationship between television watching, energy intake, physical activity and obesity. The results showed a closer link between watching television and obesity than between watching television and physical activity, in part because most of the children couldn't remember how much they exercise.
Physical activity is harder to quantify.
Nevertheless, if they're watching TV, they aren't exercising. Crespo said that the lack of physical activity was particularly evident for girls between 14 and 16, when less than one-third are active. But this may be more of a safety issue, the report says. Many girls who live in low-income neighborhoods tend to stay indoors rather than risk being harmed on the streets or in public. Many kids are home alone after school and with little else to do, they watch TV and they eat.