Relationships between media use, body fatness and physical activity in children and youth: a meta-analysis

Abstract

OBJECTIVE:To review the empirical evidence of associations between television (TV) viewing, video/computer game use and (a) body fatness, and (b) physical activity. DESIGN: Meta-analysis. METHOD: Published English-language studies were located from computerized literature searches, bibliographies of primary studies and narrative reviews, and manual searches of personal archives. Included studies presented at least one empirical association between TV viewing, video/computer game use and body fatness or physical activity among samples of children and youth aged 3-18 y. MAIN OUTCOME MEASURE: The mean sample-weighted corrected effect size (Pearson r). RESULTS: Based on data from 52 independent samples, the mean sample-weighted effect size between TV viewing and body fatness was 0.066 (95% CI ¼ 0.056-0.078; total N ¼ 44 707). The sample-weighted fully corrected effect size was 0.084. Based on data from six independent samples, the mean sample-weighted effect size between video/computer game use and body fatness was 0.070 (95% CI ¼ À0.048 to 0.188; total N ¼ 1722). The sample-weighted fully corrected effect size was 0.128. Based on data from 39 independent samples, the mean sample-weighted effect size between TV viewing and physical activity was À0.096 (95% CI ¼ À0.080 to À0.112; total N ¼ 141 505). The sample-weighted fully corrected effect size was À0.129. Based on data from 10 independent samples, the mean sample-weighted effect size between video/computer game use and physical activity was À0.104 (95% CI ¼ À0.080 to À0.128; total N ¼ 119 942). The sample-weighted fully corrected effect size was À0.141. CONCLUSION: A statistically significant relationship exists between TV viewing and body fatness among children and youth although it is likely to be too small to be of substantial clinical relevance. The relationship between TV viewing and physical activity is small but negative. The strength of these relationships remains virtually unchanged even after correcting for common sources of bias known to impact study outcomes. While the total amount of time per day engaged in sedentary behavior is inevitably prohibitive of physical activity, media-based inactivity may be unfairly implicated in recent epidemiologic trends of overweight and obesity among children and youth. Relationships between sedentary behavior and health are unlikely to be explained using single markers of inactivity, such as TV viewing or video/computer game use.

Sedentary Behavior and Dietary Intake in Children, Adolescents, and Adults

“…Overall, therefore, diet and sedentary behavior in young people is coupled and may better explain associations between sedentary behavior and weight status than other behaviors, such as a displacement of physical activity. Review-level data shows the association between weight status and screen time in young people to be quite small 8 and this could be explained by our findings. Given that physical activity can co-exist with screen time 8 , and dietary behaviors associated with sedentary time may not necessarily reflect consumption of food and drink at other times, the association between screen time and weight status is likely to exist but be small or inconsistent, notwithstanding the well known problems in the use of self-report measures for both exposure and outcome variables.…”

“…The relationship between sedentary behavior and weight status is often small or inconsistent 8,13,72 and this may be explained by the moderating effect of diet, especially dietary intake during certain types of sedentary behaviors, such as TV viewing.…”

“…For example, while there has been a longstanding assumption that TV viewing in youth is associated with overweight and obesity, 7 a meta-analysis of mainly cross-sectional studies found that the strength of such an association was actually very small. 8 Moreover, a review of sedentary behavior intervention studies showed inconsistent weight loss for young people. 9 In addition, while cross-sectional data on screen time in 10-16 year olds from 34 countries showed higher degrees of overweight with increased TV viewing in 65% of the countries, this leaves more than one-third having no association.…”

Children with a TV in their bedroom at higher risk for being overweight

“…Parents of overweight children could then be encouraged to remove the TV from their child's bedroom. Whereas some researchers have questioned the clinical relevance of limiting amount of TV viewing to prevent child overweight, 51 there are additional reasons why parents are encouraged to limit their children's TV time and to remove the TV from their bedrooms. As discussed earlier, high levels of child TV viewing are associated with many negative outcomes, including decreased school performance and poor diet quality, and the American Academy of Pediatrics Committee on Public Education recommends that pediatricians should encourage parents to remove television sets from their children's bedrooms.…”

Physical activity and sedentary behavior: a review of longitudinal studies of weight and adiposity in youth

“…93 A meta-analysis of 39 studies (mostly cross-sectional) of sedentary behavior and obesity yielded a statistically significant, although small, effect size. 94 As with cross-sectional studies on physical activity and development of obesity, the cross-sectional design also limits the determination of cause and effect for sedentary behavior. Perhaps children watch more TV because their obesity makes it more difficult to exercise due to physical limitations, or due to social isolation; compared to normal-weight adolescents, overweight adolescents have fewer friends and are more likely to have no friends, as assessed by friendship 'nominations' by peers.…”