Television viewing and obesity: a prospective study in the 1958 British birth cohort

Objective: To assess whether frequency of television viewing in adolescence (11 and 16 years) or early adulthood (23 years) affected subsequent changes in body mass index (BMI) through to mid-adulthood life, and waist-hip ratio in mid-adulthood. Subjects: The 1958 British birth cohort includes all births in 1 week in March 1958 in England, Scotland and Wales. The main analyses included at least 11 301 participants. Outcome measures included BMI at 16, 23, 33 and 45 years and waist-hip ratio at 45 years. Results: Watching television 'often' at 16 years (but not 11 years) was associated with a faster gain in BMI between 16 and 45 years in males (0.011 kg m-2 per year, 95% confidence interval (CI) 0.003, 0.019) and females (0.013 kg m-2 per year, 95%CI 0.003, 0.023). More frequent television viewing at 11, 16 and 23 years was associated with a faster gain in BMI between 23 and 45 years in females, but not in males. Television viewing at 23 years was associated with waist-hip ratio at 45 years: participants watching >or= 5 times per week had a waist-hip ratio 0.01 higher than those watching less often. At 45 years, those watching television for >or= 4 h day-1 had a waist-hip ratio 0.03-0.04 higher than those watching for