Nutrition, physical activity and behavior-modifying techniques are widely applied components of interventions treating obesity. Our aim was to review available information on the short and long term effects of intervention treatment on body fat composition of overweight and obese children and adolescents and, to obtain a further understanding on how different body composition techniques detect longitudinal changes. In total, thirteen papers were included; seven included a multidisciplinary intervention component, five applied a combined dietary and physical activity intervention and one a physical activity intervention. Body composition techniques used included anthropometric indices, bioelectrical impedance analysis, and dual energy X-ray absorptiometry. Percentage of fat mass change was calculated in when possible. Findings suggested, no changes were observed in fat free mass after 16 weeks of nutritional intervention and the lowest decrease on fat mass percentage was obtained. However, the highest fat mass percentage with parallel increase in fat free mass, both assess by DXA was observed in a multicomponent intervention applied for 20 weeks. In conclusion, more studies are needed to determine the best field body composition method to monitor changes during overweight treatment in children and adolescents.