Greater TV, computer, video game and other media exposure time in children is increasing and is associated with adverse health outcomes such as becoming overweight.12,14,31
Some studies have reported null results between TV viewing and overweight status in children,32,33
but the current findings are consistent with several reports showing TV viewing to be directly associated with children becoming overweight.7,11–14,19,34–36
The present study showed that 1 additional hour of TV watching or total screen time per day increased the odds of being overweight by 20%–30%. Not surprisingly, the study revealed that overweight children reported watching more TV than their nonoverweight counterparts, and those children who had at least one overweight parent tended to watch more hours of TV viewing than children of normal-weight parents.
In a cross-sectional study of a nationally representative sample of 1483 youth and their parents, parental weight moderated the relationship between hours of TV viewing and overweight status among adolescent girls and boys, but not among younger children.19
In a longitudinal study of adolescent girls, TV viewing predicted increases in BMI for girls with overweight parents but not for girls with normal-weight parents.37
In the present study, parental weight status significantly modified the relationship of TV watching and total screen time with body composition among children of all ages. BMI and PBF were positively associated with hours of TV viewing or total screen time per day in children of overweight/obese parents, but not in children of normal-weight parents.
A mechanism for explaining the association between TV viewing and overweight is thought to be the combination of reduced physical activity and adoption of unhealthy eating patterns. Time spent watching TV or using a computer or other media is time missed from being physically active. In general, children whose levels of physical activity are low may be watching more TV than active children.17,38
TV watching is also associated with increased snacking and consumption of high-fat, high-sugar, or high-calorie foods3,4,39–43
and low intakes of fruit and vegetables,44
all of which have been associated with greater BMI. However, energy intake and physical activity were not related to BMI or PBF, or to hours of TV viewing or total screen time in the present study.
The findings of the current study also support the evidence that obesity is familial. Parental obesity is a strong predictor of overweight and obesity in children.2,3,15,45
Family studies have found that parental patterns of TV watching influence those of their children. Children who watch more than 2 hours of TV per day generally have parents who are high-exposure TV viewers.3,4,17,18,46
Previous studies of physical activity have demonstrated that parental support of their children’s participation in physical activity produces active children.47,48
Thus, it is reasonable to conclude that the influence or support of parents may promote their children’s involvement in physical activity or inactivity, which ultimately has an impact on their children’s body composition. A recent survey of youth aged 8–18 years reported their overall time of media use, including time devoted to TV viewing, video gaming, using a computer, listening to music, reading, and using a telephone was 6.5 hours in 2004.31
Clearly, the use of technology has increased since the present study was conducted, and therefore, the concern for the increased prevalence of overweight and obesity in our society is warranted.
This study had several limitations. First, the cross-sectional study design limits any cause–effect conclusions from being drawn from these study findings. Second, although data were available from 526 boys and girls aged 8, 11, and 14 years, sample size may have limited the ability to detect a significant interaction between parent and child characteristics in the logistic regression models. Third, TV viewing was assessed for one 24-hour period at baseline and may not represent usual TV viewing habits of children. Further, the day of the interview was at the convenience of the parent and child, and therefore, standardization of weekday or weekend day was not considered. However, several studies have reported similar findings that overweight children report more hours of TV viewing.11–14
Fourth, parental height and weight information was obtained by self-report. Self-reported height is usually overestimated and weight underestimated,49
so a systematic bias toward underestimation of BMI is expected. The effect of this bias would likely attenuate the effect of parental BMI on the relationship of child’s hours of TV viewing with BMI. Finally, no information about patterns of parent TV watching was available in this study. On the other hand, the strengths of this study include the study design and the standardized procedures used in data collection, such as recording detailed TV program information to obtain a precise estimate of TV viewing hours.
The effect of parental overweight status on children’s body mass may have both genetic and environmental links, especially when parents influence their children’s TV viewing habits.4,17,18,47
Therefore, it would be important to target family TV viewing behaviors in weight-management and obesity-prevention strategies. Watching TV, as a sedentary behavior with exposure to adverse dietary messaging, has been associated with negative health effects on children and adolescents, including reduced physical activity, violence, substance use, and other negative behaviors.50
The American Academy of Pediatrics recommends that parents limit daily TV time to 1–2 hours per day of quality programming, remove TV sets from children’s bedrooms, and encourage alternative entertainment, such as athletics and other individual physical activities. TV viewing increases the likelihood for overweight in childhood11–14,19,34,35
and from childhood into adulthood.51
Therefore, interventions to influence obesity by reducing sedentary behaviors, particularly TV viewing, should begin in early childhood.5–8