Physical Activity, Sedentary Time, and Diet as Mediators of the Association Between TV Time and BMI in Youth

Purpose: This study examined dietary indicators, sedentary time, and physical activity as potential mediators of the association between TV time and BMIz in youth. Design: Cross-sectional study in 2 independent samples of youth. Setting: Data collection occurred by mail and telephone for adolescents and either at home or in medical settings for children. Sample: 928 youth ages 12-16 and 756 youth ages 6-12 and a parent. Measures: TV time, snacking/eating while watching TV, and a 3-day dietary recall were assessed via child/parent report. Physical activity and sedentary time were assessed by accelerometer wear. Analysis: Direct and indirect associations (through 8 diet and activity variables) of TV time with BMIz were tested in boys and girls in each sample. Results: TV time had a positive association with BMIz in 6-12 year old boys and girls. Direct associations emerged between TV time and the diet/activity variables, and between diet/activity variables and BMIz. Snacking/eating while watching TV had a significant positive association with BMIz in younger boys and mediated the association between TV time and BMIz ( β = .06, p = .019; 25% attenuation). Conclusions: Snacking/eating while watching TV may be a possible reason TV time is consistently associated with obesity in youth. Targeting reductions in TV time and associated snacking could improve health impacts.