| This study examines the relationship between problematic social media use, self-objectification, and body image disturbance in women, with physical activity and diet intensity as moderators. It also explores the psychological outcomes of depression and anxiety. A cross-sectional study was conducted with 594 women aged 18-65 in Istanbul, Türkiye. Participants completed validated measures assessing social media use, self-objectification, body image disturbance, physical activity, diet intensity, depression, and anxiety. A moderated mediation analysis was performed. Self-objectification significantly mediated the relationship between problematic social media use and body image disturbance (b = 0.14, SE = 0.03, 95% CI [0.10, 0.21], p < 0.01,  = 0.18). Physical activity buffered this effect (b = -0.12, SE = 0.05, p = 0.02, d = 0.36), while diet intensity exacerbated it (b = 0.15, SE = 0.04, p < 0.01, d = 0.42). Body image disturbance also mediated the association between social media use and depression (b = 0.18, SE = 0.05, p < 0.01,  = 0.22) and anxiety (b = 0.16, SE = 0.04, p < 0.01,  = 0.19). The findings highlight the dual roles of physical activity and diet intensity in shaping body image outcomes. The study underscores the need for targeted interventions to mitigate the negative impact of social media-driven self-objectification on body image and mental health. |