Screen time predicts weight gain but body fatness did not predict more screen time in boys

Screen time, i.e. TV viewing and computer time, has been found to be associated with overweight in children and adolescents. However, it is unclear if kids who are overweight start watching more TV or if kids who watch more TV are more likley to become overweight. The aim of a study just published in the International Journal of Behavioral Nutrition & Physical Activity examined the direction of the association between screen time and body fatness in Dutch adolescents. Dr. Teatske Altenburg was first author.

Longitudinal data of 465 Dutch adolescents (mean age at baseline 13 years, 53% boys) was used. Body fatness (objectively measured Body Mass Index (BMI), four skin folds and waist- and hip circumference), self-reported time spent watching TV and computer use, and aerobic fitness (shuttle run test) were assessed in all participants at three time points during 12 months. State of the art statistical analyses were conducted to see if screen time predicted body fatness in the following time period and/or whether body fatness predicted more screen time.

Time spent TV viewing did indeed predict changes in BMI and hip circumference in boys, but not in girls, in the subsequent period. Computer time significantly predicted increases in skinfolds in boys and girls and increases in BMI in girls. Body fatness did not predict any changes in screen time.
Our study thus only partly supports the widely posited hypothesis that more  screen time cause increases in body fatness. In addition, this study demonstrates that high levels of body fatness did not predict increases in screen time.