Watching television is associated with childhood obesity: but is it clinically important?
OBJECTIVE
To assess the impact of television viewing during childhood and adolescence on body mass index (BMI) in children up to the age of 15 years.


METHODS
Unselected birth cohort, assessed at birth and every 2 years from age 3 to 15 years.


METHODS
In all, 1037 individuals were assessed at age 3 years. At age 15 years, 976 (95% of living cohort) continued to participate.


METHODS
Parental estimates of weekday television viewing between age 5 and 11 years. Self-reports of television viewing at age 13 and 15 years. Weight and height were measured at each age to calculate BMI.


RESULTS
BMI and prevalence of overweight at all ages were significantly associated with mean hours of television viewing reported in the assessments up to that age. These associations were stronger in girls than boys. The associations remained significant after adjusting for parental body mass indices and socio-economic status.


CONCLUSIONS
Time spent watching television is a significant predictor of BMI and overweight in childhood. Although the effect size appears small, it is larger than the effect sizes commonly reported for nutritional intake and physical activity. Television viewing should be regarded as an important contributing factor to childhood obesity.
Hancox
R J
RJ
Dunedin Multidisciplinary Health and Development Research Unit, Department of Preventive and Social Medicine, Dunedin School of Medicine, University of Otago, New Zealand. bob.hancox@otago.ac.nz
Poulton
R
R
D000293:Adolescent; D000294:Adolescent Behavior / Q000502:physiology; D015992:Body Mass Index; D002648:Child; D002652:Child Behavior / Q000502:physiology; D002675:Child, Preschool; D004812:Epidemiologic Methods; D006801:Humans; D009520:New Zealand / Q000453:epidemiology; D009765:Obesity / Q000453:epidemiology / Q000209:etiology*; D012737:Sex Factors; D013690:Television; D013997:Time Factors