The associations between TV viewing, food intake, and BMI. A prospective analysis of data from the Longitudinal Study of Australian Children

Objective: Despite cross-sectional evidence of a link between TV viewing and BMI in early childhood, there has been limited longitudinal exploration of this relationship. The aim of the present study was to explore the potential bi-directionality of the relationship between TV viewing and child BMI. A secondary aim was to evaluate whether this relationship is mediated by dietary intake. Study design: Parents of 9064 children (4724 recruited at birth, 4340 recruited at age 4) from the Longitudinal Study of Australian Children (LSAC) completed measures of their child's dietary intake and TV viewing habits at three equidistant time points, separated by 2 years. Objective measures of height and weight were also obtained at each time point to calculate BMI. Cross-lagged panel analyses were conducted to evaluate potential bi-directional associations between TV viewing and child BMI, and to evaluate mediation effects of dietary intake for this relationship. Results: Our longitudinal findings suggest that the relationship between TV viewing and BMI is bi-directional: Individuals who watch TV are more likely to gain weight, and individuals who are heavier are also more likely to watch TV. Interestingly, dietary intake mediated the BMI-TV viewing relationship for the older children, but not for the birth cohort. Conclusions: Present findings suggest that sedentary behaviours, particularly when coupled with unhealthy dietary habits, constitute a significant risk factor for excessive weight gain in early childhood. Interventions targeted at helping parents to develop healthy TV viewing and eating habits in their young children are clearly warranted. (C) 2012 Elsevier Ltd. All rights reserved.