Physical activity moderates links between weight misperception and adolescent mental wellbeing: an international cross-sectional study

Abstract Objective To examine whether physical activity (PA) moderates the association between weight misperception and mental wellbeing among adolescents. Methods 296,648 adolescents (aged 11, 13 and 15 years) participating in the Health Behaviour in School-aged Children study (2014, 2018) across Europe and North America were included for analysis. Weight misperception was analysed as perceptual inaccuracy (absolute discrepancy between perceived and actual weight status) and directional misperception (signed discrepancy indicating over/underestimation). PA was assessed via frequency of moderate-to-vigorous PA (MVPA, days per week) and vigorous PA (VPA, times per week). Mental wellbeing outcomes included life satisfaction and psychosomatic complaints. Moderation analyses used linear regression with interaction terms, evaluating polynomial models for directional misperception when appropriate. Average marginal effects were computed across PA strata with false discovery rate (FDR) adjusted significance testing and cluster-robust standard errors. Results Greater weight misperception was associated with lower life satisfaction and more psychosomatic complaints. PA significantly moderated these associations. For life satisfaction, both MVPA and VPA buffered the adverse associations of both misperception types. For psychosomatic complaints, both MVPA and VPA attenuated associations with perceptual inaccuracy, while only VPA buffered directional misperception associations. The moderation was most robust for perceptual inaccuracy, with approximately 38% attenuation in the life satisfaction association at the highest MVPA levels. Conclusions Higher levels of PA are associated with an attenuated adverse association between weight misperception and mental wellbeing in adolescents. These findings suggest that promoting PA may help safeguard mental wellbeing among adolescents experiencing weight misperception.