In a commentary published in the same issue of the American Journal of Preventive Medicine, Stuart J.H. Biddle, from the School of Sport and Exercise Sciences, Loughborough University, UK, cautions that studies of TV viewing are part of a recent trend to study sedentary behaviors in general, and such studies are difficult to interpret.
He argues, There is much debate concerning whether TV viewing is associated with obesity in young peopleFor example, an extensive meta-analysis of mainly cross-sectional studies showed that the relationship is very smallMoreover, the small relationship may be a reflection of other trendsIf obesity is causally related to TV viewing, as some suggest, how do we account for the following paradoxes: (1) obesity levels are increasing but TV viewing figures are not, (2) obesity increases during adolescence at the same time that TV viewing decreases, and (3) boys watch more TV than girls but show less obesity and greater physical activity" Whatever the true findings, the association between sedentary behavior (TV viewing or other behaviors) and health outcomes, at least in youth, is likely to be complex and, as yet, unknown.
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