Heavy Screen Use on Weekends in Childhood Predicts Increased Body Mass Index in Adolescence: A Three-Year Follow-Up...

We aimed to examine whether sedentary screen time changes when transitioning from childhood to adolescence and whether children's screen time, separately for school days and weekends, affects body mass index (BMI) in adolescents.

This prospective 3-year follow-up study included 5,084 children with a mean (standard deviation) age of 11 (1) years at baseline and 14 (1) years at follow-up. Children reported screen time, more specifically, time spent viewing TV programs and using a computer outside school while sitting. We categorized children into light, medium, and heavy TV viewers and computer users separately for school days and weekends. We also calculated the age- and gender-specific BMI z-score (BMIz).

Time spent viewing TV changed from baseline to follow-up on school days and on weekends (p < .001 for both); the proportion of heavy TV viewers on school days (≥3 h/d) increased from 16% to 23% and on weekends (≥4 h/d) from 19% to 30%. Heavy TV viewers and computer users on both school days and on weekends had a higher BMIz 3 years later (p < .001 for all). After adjusting for age, gender, language, baseline BMIz, sleep duration, eating habits, exercise, and the other screen-time variables, heavy TV viewing on weekends remained significantly associated with an increased BMIz at follow-up (B = .078; p = .013).

The proportion of heavy screen users increases when transitioning from childhood to adolescence. Moreover, heavy screen use, especially on weekends in 11-year-old children, is associated with an increased BMI 3 years later.