Social media use and disordered eating in young adults: the protective and risk pathways of physical activity and body image

Background/objectives Social media is a pervasive force in youth culture, shaping body perception and dietary habits. However, the psychological and behavioral pathways linking social media use to eating behavior remain insufficiently understood. This study examined the mediating roles of body image dissatisfaction and physical activity in the association between social media use and dietary behavior among young adults. Methods A cross-sectional survey was conducted among 422 Chinese university students (Mean age = 22.82 ± 2.42) between November 2024 and February 2025. Participants completed validated measures of social media use, body image dissatisfaction (BSQ-16), physical activity (IPAQ-SF), and dietary behavior (DEBQ). Data were analyzed using confirmatory factor analysis (CFA), parallel mediation modeling (PROCESS macro), and ANOVA for subgroup comparisons. Results Confirmatory factor analysis confirmed the measurement model (CFI = 0.926, RMSEA = 0.057). Social media use significantly predicted higher body image dissatisfaction (β = 0.578, p < 0.001) and lower physical activity (β = −348.717, p < 0.001), both of which were associated with disordered eating (β = 0.442 and β = −0.000, respectively). Parallel mediation analysis identified two significant indirect effects: through body image dissatisfaction (indirect effect = 0.256, p < 0.001) and physical activity (indirect effect = 0.084, p < 0.001). ANOVA showed that lower physical activity was associated with higher social media use and poorer dietary outcomes. Conclusion Social media is associated with dietary behavior through dual psychological and behavioral pathways. Interventions should target body image resilience and active lifestyles to mitigate the health risks posed by digital media environments.