OBJECTIVE: To analyse the association of time watching television (TV) and physical activity with obesity in the Mediterranean area of Spain with the highest prevalence of obesity. DESIGN: Cross-sectional study. SETTING: Valencia Region in Spain. PARTICIPANTS: A representative sample of 814 men and 958 women, aged 15 y and older, participating in a Health and Nutrition Survey conducted in 1994. MEASUREMENTS: Height and weight were directly measured during home interviews. The outcome measure was obesity, defined as a body mass index  30 kg/m2. Covariates were self-reported hours of TV viewing, physical activity habits, sleeping duration, age, gender, educational level, smoking and marital status. Prevalence odds ratios (POR) estimated by logistic regression were used as effect measures. RESULTS: Obese people reported to spend more time watching TV (mean±s.d.: 3.6±1.5 h/day) than non-obese ones (3.0±1.4 h/day), and less sleeping time. In multivariate analysis, obesity was associated with TV viewing, sleeping time and physical activity at work. People watching TV 4 h/day showed a higher adjusted prevalence odds ratio of obesity, POR=2.38 (95% confidence interval, 1.54-3. 69), compared with those watching TV £1 h/day. People who reported to sleep 9 h/day presented a lower POR of obesity than those sleeping £6 h/day, POR=0.43 (0.27-0.67). Statistically significant dose-responses were observed for both associations, so that the prevalence odds ratio of obesity was 30% higher for each hour of increased TV viewing and 24% lower for each additional hour of sleeping time. In addition, the prevalence of obesity was lowest among single people, those more physically active at work, and those with a high educational level. CONCLUSION: Time spent watching television and a low physical activity at work were related to obesity in adults. The inverse association between obesity and sleep duration deserves further research. International Journal of Obesity (2000) 24, 1683-1688 | 
