It is unclear from these results whether sports programs , as currently offered , protect youth from becoming overweight or obese .
Sport is a promising setting for obesity prevention among youth , but little is known about whether it prevents obesity .
Total energy intake, adolescent discretionary behaviors and the energy gap
Objective : To estimate total energy intake and the energy gap — the daily imbalance between energy intake and expenditure — associated with discretionary behaviors of adolescents , namely their leisure active behaviors ( playing or participating in sports and heavy chores ) , leisure sedentary behaviors ( television ( TV ) viewing and playing video and computer games ) , productive sedentary behaviors ( reading or doing homework ) . Design : Prospect i ve observational study . Participants : A total of 538 students ( mean age at baseline=11.7 years ) from public schools in the Boston area studied prospect ively from the fall of 1995 to the spring of 1997 . Measurements : Anthropometric assessment including height and weight , dietary assessment using a youth food frequency question  naire and measures of TV , video , reading/doing homework and youth physical activity .  Results : We estimate the change in total energy intake for each hour change in discretionary activity using regression methods . A 1-h increase in watching TV is associated with a 106 kcal h−1 increase in total energy intake ( 95 % confidence interval ( CI ) : 61–150 kcal day−1 ) . A similar change of 92 kcal h−1 ( 95 % CI : 37–147 kcal day−1 ) is seen with playing video and computer games . The change in energy intake associated with an hour change in physical activity is 292 kcal h−1 ( 95 % CI : 262–321 kcal day−1 ) . No significant change is associated with reading/doing homework . Assuming that typical energy expenditures are associated with these behaviors , reading/doing homework appears to be an ‘ energy neutral ’ activity , whereas watching TV and playing video and computer games is associated with an energy surplus . If we assume that physical activity levels are moderate ( 3.5 METs ) , then this is also an energy surplus activity . If physical activity is assumed to be vigorous for the entire time allotted ( > 6.0 METs ) , an energy deficit could be achieved . We vali date d these estimates by calculating regressions predicting change in weight . Results indicate that each hour increase in TV viewing is associated with a weight increase of 0.38 kg ( 95 % CI : 0.17–0.59 kg ) , with no significant associations for the other behaviors . A model with change in BMI as the dependent variable produced similar results . Conclusion : Watching TV is an activity associated with a daily energy surplus . Although physical activity is thought of as an energy deficit activity , our estimates do not support this hypothesis . Reading/doing homework is the only discretionary activity examined which appears to be clearly energy neutral . The differential impacts of these discretionary behaviors on energy intake and the energy gap are discussed in relation to food-related advertisements aim ed at children and adolescents
It is unclear from these results whether sports programs , as currently offered , protect youth from becoming overweight or obese .
Sport is a promising setting for obesity prevention among youth , but little is known about whether it prevents obesity .