Objectives: To examine the associations of TV viewing time and domain-specific physical activity with weight change; to determine whether domain-specific physical activity moderates the potential association of TV viewing time with weight change.
Methods: We used four-year longitudinal data (baseline: 2003-2004, follow-up: 2007-2008) on 969 adults from selected neighborhoods in Adelaide, Australia (Age: 48.6 ± 10.6 years, 61% females). Mixed models examined four-year weight change as the dependent variable, with TV viewing time, habitual transport and past week domain-specific physical activity at baseline as independent variables.
Results: On average, participants gained 1.6 kg over four years. TV viewing time at baseline was positively associated with weight gain at follow-up. Each additional hour of TV viewing was associated with 0.24-0.27 kg of extra weight gain. This relationship was not moderated by recent recall of transport, leisure-time, and occupational physical activity, but was moderated by habitual transport: an additional hour of TV viewing time at baseline was significantly associated with an extra weight gain of 0.65 kg at follow-up among those who were inactive in everyday transport; TV time was not significantly associated with weight change among those who were regularly active in transport.
Conclusion: Habitual active transport may protect adults against risk of weight gain associated with prolonged TV viewing time.
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