Background: An inverse relationship between physical activity (PA) and depression among adolescents has been reported in developed communities without consideration of sedentary behaviors (SB, including sitting for course study, viewing TV, and sleeping). We explored the association between recreational PA time (hr/wk) and depression after adjustment with SB and other possible confounders among Chinese adolescents.

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Objective: To examine the relationship between television (TV) viewing and body mass index (BMI) among adolescents in a region of mainland China. Design: Population-based cross-sectional study, conducted between September and November of 2004, on a sample of enrolled high-school students aged 12-18 years. Setting: One hundred and sixty-eight classes randomly selected from both urban and rural areas and belonging to 15 senior and 41 junior high schools in Nanjing, China, with a regional population of 6Á0 million. Subjects: In total 6848 students participated; 47Á7 % from urban and 52Á3 % from rural areas; 49Á0 % male and 51Á0 % female. The response rate among eligible participants was 89Á3 %. Results: The proportion of overweight was 6Á6 % according to the criteria of overweight recommended for Chinese adolescents. Boys than girls (8Á9 % vs. 4Á4 %) had higher odds of being overweight (odds ratio (OR) 2Á12, 95 % confidence interval (CI) 1Á74, 2Á60), while the proportion of overweight was significantly lower among rural students than urban students (4Á5 % vs. 8Á9 %; OR 0Á49, 95 % CI 0Á40, 0Á60). Those students who watched TV for more than 7 h/week had a 1Á5 times greater odds of being overweight relative to their counterparts who watched TV for 7 h/week or less (adjusted OR 1Á51, 95 % CI 1Á24, 1Á82). Furthermore, there was a positive linear relationship between TV viewing time and BMI, even after adjusting for age, gender, residence area, time spent in study, in sleeping and in physical activity, and monthly pocket money. Conclusions: Viewing TV might increase the likelihood of being overweight for Chinese adolescents in China.