Sedentary behaviors and adiposity in young people: causality and conceptual model

• Sedentary behavior — sitting time — has long been thought to be a risk factor for pediatric obesity, especially through television and other screen viewing, with claims made for clear and causal links. • A closer look at the literature reveals a complex picture of statistically significant but small associations for screen time and adiposity in youth, but small or no associations for total sedentary time assessed with accelerometers. • Current evidence does not support a causal association. • Results concerning obesity may depend on a variety of mediating, moderating, and confounding factors including light and moderate-to-vigorous physical activity, diet, and sleep. • Reducing sedentary behavior in youth probably is sensible, but we propose that the field is more complex than sometimes recognized.