Longitudinal associations between television in the bedroom and body fatness in a UK cohort study

OBJECTIVE: To assess longitudinal associations between screen-based media use (television (TV) and computer hours, having a TV in the bedroom) and body fatness among UK children. METHODS: Participants were 12 556 children from the UK Millennium Cohort Study who were followed from age 7 to age 11 years. Associations were assessed between screen-based media use and the following outcomes: body mass index (BMI), fat mass index (FMI), and overweight. RESULTS: In fully adjusted models, having a bedroom TV at age 7 years was associated with significantly higher BMI and FMI (excess BMI for boys=0.29, 95% confidence interval (CI) 0.06–0.52; excess BMI for girls=0.57, 95% CI 0.31–0.84; excess FMI for boys=0.20, 95% CI 0.04–0.37; excess FMI for girls=0.39, 95% CI 0.21–0.57) and increased risk of being overweight (relative risk (RR) for boys=1.21, 95% CI 1.07–1.36; RR for girls=1.31, 95% CI 1.15–1.48) at age 11 years, compared with having no bedroom TV. Hours spent watching TV or digital versatile disks were associated with increased risk of overweight among girls only. Computer use at age 7 years was not related to later body fatness for either gender. CONCLUSION: Having a TV in the child’s bedroom was an independent risk factor for overweight and increased body fatness in this nationally representative sample of UK children. Childhood obesity prevention strategies should consider TVs in children’s bedrooms as a risk factor for obesity.