Background:

explaining why and how overweight prevention programs were effective was a real need; especially the potential role of physical activity (PA) and sedentary behavior (SB) should be highlighted. This study aimed to evaluate the 2-year effectiveness of a screening and care strategy in adolescents’ weight reduction with regards to PA and SB change.

Methods:

1745 adolescents aged 15.1 years from PRALIMAP trial was included (n = 840 for screening and care group and n = 905 for control group). PA and SB time (international physical activity questionnaire: IPAQ), body mass index (BMI), and BMI z-score were assessed at inclusion and after 2-year intervention. Hierarchical mixed models were applied.

Results:

Compared with the control group, screening and care strategy was associated with an increase in global PA (58 min/week), a moderate PA (43 min/week), the adherence to the French PA guidelines (OR = 1.3), and a decrease in SB (−198 min/week). The 2-year weight change decreased when adjusted for PA and SB suggesting that the effect of screening and care strategy was partly mediated by PA and SB.

Conclusion:

Screening and care intervention seemed to be effective in increasing PA and decreasing SB. The induced PA and SB modifications contributed to the observed weight change.