Obesity and sedentarism in children and adolescents: what should be bone?

Paediatric overweight continues to be a public health problem, and the etiology of obesity is multifactorial and complex. Dietary patterns, physical activity (PA) and sedentary behaviors are acknowledged as major behavioural determinants of obesity. New technologies and electronic based activities have produced a decrease in PA levels, and an increase in sedentary activities in children and adolescents. Potential mechanisms that explain the association between TV viewing and childhood obesity are: displacement of PA, unhealthy food preferences produced by food advertisements, a higher energy intake by automatic eating and overconsumption caused by distraction. Interventions aimed to reduce time in sedentary behaviours are in children generally positive. However, their benefits on adiposity markers are small. Thus, if global and macro-level obesogenic factors are not changed substantially, the interventions oriented to prevent obesity will produce small benefits.