The aim of this study was to assess the effects of age and type of physical activity on anthropometric measures of obese youth participating in an intervention programme. Subjects included 37 obese children (12·5 ± 2·9 years). The programme consisted of a unique programme of physical activity and health education. Assessments included body mass index (BMI), body composition and ability to perform sport activities. Paired t‐tests were used to assess the effects of intervention, and chi square was used to assess interaction between measures. Findings suggest significant decrease in Z‐scores of BMI and an improvement in the ability to perform sport activities (P<0·05). The effectiveness of the programme has more impact on children than adolescents (P<0·05). Improvements were greater in team versus net sports (P<0·05). Results show that intervention strategies have to be different according to the age to have a favourable effect on anthropometric characteristic and the consequences of obesity childhood and adulthood. The findings suggest that the intervention programme was of greater benefit for children than adolescents.