Background Adolescent overweight is a major public health concern, as it is associated with several short-run and long-run adverse health outcomes. Inappropriate health behaviours may be at the front of this epidemic. There is widespread need for new strategies that may positively influence dietary and physical activity behaviours. This trial (NCT02941770) was designed to investigate the impact of a physical activity consultation, based on motivational interview technique, on physical activity behaviour and weight status among overweight adolescents followed at a tertiary paediatric care centre.

Methods/Design This is an ongoing non-randomised controlled clinical trial with a 6-month duration and follow-up at month 12. It is expected to be concluded in December 2018. Adolescents (n=129) aged 12–18 with a body mass index ≥p85 are recruited and allocated into three groups: (1) control group: standard care (paediatric and nutrition consultations, n=43); (2) experimental group I: standard care plus physical activity consultation (n=43); and (3) experimental group II: exposure to two sessions/week of structured physical exercise, in addition to the standard care plus physical activity consultations (n=43). Sample size was calculated according to power analysis. Participants undergo a set of socioeconomic, anthropometric, body composition, clinical and behavioural (dietary and physical activity) assessments.

Discussion Adolescence is a critical period for the acquisition of a healthy lifestyle. The promotion of an active lifestyle may influence adolescents’ weight status and further prevent multiple comorbidities. The findings of our study will provide further understanding on the impact of a physical activity consultation on physical activity behaviour and weight reduction/maintenance among overweight adolescents.

Trial registration number NCT02941770.