Inactivity, diet, and the fattening of America.

Recent studies have documented an increasing prevalence of childhood and adolescent obesity in the United States. These increases will likely result in increased adult obesity because of the tracking of fatness from adolescence into adulthood and the tendency for adults in the United States to become obese as they age. We have identified television viewing as a strong risk factor for childhood and adolescent obesity. Television viewing is associated with both the onset of obesity and a decrease in the remission of obesity and acts by decreasing activity levels and possibly influencing diet. Logistic regressions also document associations between television viewing and obesity among adults. These relationships are greater than those estimated between measures of vigorous physical activity and obesity and indicate the importance of inactivity, to which television viewing contributes substantially. Population dietary intake data indicated no statistically significant change and perhaps some decrease in mean energy intake among children and youth during the same period that obesity was increasing. These data are consistent with the hypothesis that decreases in activity reduce lean body mass and lower energy requirements. We conclude that multiple intervention approaches involving diet, exercise, and restriction of television viewing and other sedentary activities all appear necessary to halt the fattening of America.