One in every 3 Portuguese adolescents is overweight (14% obese) (ONOCOP, 2009). Several institutions state that prevention is of upmost importance to deal with this epidemic (Council on Sports Medicine and Fitness; Council on School Health, 2006, August et al, 2008, Kohn et al, 2006), but public health stakeholders should also increase their efforts to treat those who already have excessive weight (Oude Luttikhuis et al, 2009). Several facts support this need, namely that obesity in adolescence: a) has a significant impact on both physical and psychosocial health (Lobstein et al, 2004); b) is an independent risk factor for adult obesity (Singh et al, 2008); c) is an independent risk factor for all cause mortality in adulthood - a more powerful predictor than being overweight in adult (Must et al, 1992); and d) is a major threat to the steady rise in life expectancy that occurred during the past two centuries (Olshansky et al, 2005).