BoPo online, BoPo offline? Engagement with body positivity posts, positive appearance comments on social media, and adolescents' appearance-related prosocial tendencies

Encouraging prosocial tendencies toward others' physical appearance is crucial for promoting a positive body image during adolescence. Social media content that highlights positive appearance messages can significantly influence these tendencies. Hence, this three-wave panel study explored the impact of exposure to and the posting of Body Positivity (BoPo) posts and positive appearance comments on social media upon adolescents' offline prosocial behavioral tendencies towards others’ appearances, as mediated by appearance-related prosocial reasoning. Using a sample of adolescents aged 12 to 18 (N = 496, M_age = 15.05, SD = 1.49; 67.9% girls), the hypotheses received partial support. At the between-person level, adolescents who more often viewed BoPo and posted positive appearance comments also reported higher appearance-related prosocial tendencies. Nonetheless, on the within-person level, only more often posting positive appearance comments predicted a change to more appearance-related prosocial reasoning from T2 to T3. Notably, the mediation pathways from exposure to and the posting of BoPo and positive appearance comments to appearance-related prosocial tendencies through prosocial reasoning were not significant. Such findings suggest the presence of more significant sources for appearance-related prosocial tendencies than social media during adolescence. Still, the between-person findings can be valuable for peer-led campaigns that aim to foster a positive body image. Such campaigns could identify adolescents with heightened appearance-related prosocial tendencies who tend to engage with body positivity posts and positive appearance comments on social media.