Investigation of Smartphone Addiction as a Potential Mediator of the Cross-Sectional Associations Between Body Image, Physical Activity, and Eating Disorders Among University Participants

Background: Smartphone addiction can negatively affect university students by decreasing body satisfaction and physical activity and increasing eating disorders. However, the mechanisms underlying these detriments are unclear. This study investigates the associations among smartphone addiction, body image, physical activity, and eating disorders among university participants. Additionally, this study examines smartphone addiction as a potential mediator of these cross-sectional associations. Methods: Using a simple random sampling approach, 206 university students at Shaqra University were recruited for this cross-sectional study. Survey instruments included the Arabic version of the Smartphone Addiction Scale—Short Version (SAS-SV), the Body Image Questionnaire (BIQ-19), the International Physical Activity Questionnaire (IPAQ) (short version), and the Eating Disorder Examination Questionnaire (EDE-Q 6.0). To test mediational hypotheses, a structural equation model (SEM) was used in which smartphone addiction scores functioned as a mediator of the associations between (a) body image and eating disorder symptoms and (b) physical activity and eating disorder symptoms. Statistical significance was set at p < 0.05. Results: All analyses were performed in R (Version 4.4.1) using RStudio (Version: 2025.05.0+496) with the lavaan package. SEM shows that the direct effect of physical activity on eating disorder symptoms was positive and large (B = 0.64, Std. β = 0.821, SE = 0.031, 95% CI [0.576, 0.699], p < 0.001). This indicates that, after accounting for smartphone addiction and body image, higher physical activity is associated with higher eating disorder scores. The indirect effect of physical activity on eating disorder symptoms via smartphone addiction was positive and small but statistically significant (B = 0.02, Std. β = 0.025, SE = 0.01, 95% CI [0.004, 0.042], p = 0.049). This suggests that smartphone addiction partially mediates the positive relationship between physical activity and eating disorder symptoms. The total effect of physical activity on eating disorder symptoms was positive and large (B = 0.66, Std. β = 0.846, SE = 0.031, 95% CI (0.596, 0.719), p < 0.001). Body image did not significantly predict smartphone addiction scale scores (B = 0.022, Std. β = 0.038, SE = 0.046, 95% CI [−0.067, 0.112], *p* = 0.629), and the analysis did not provide evidence of an indirect association between body image and eating-disorder symptoms through smartphone addiction (B = −0.003, Std. β = −0.004, 95% CI [−0.015, 0.008], *p* = 0.659). Conclusions: The study identified a significant positive direct association between physical activity and eating disorder symptoms, with a small but statistically significant positive indirect effect via smartphone addiction. The total effect was positive. Body image did not significantly predict smartphone addiction scale score, and the analysis did not provide evidence of an indirect association between body image and eating-disorder symptoms through smartphone addiction. These findings are cross-sectional and do not establish temporal ordering or causal mediation. The small indirect estimate and its uncertainty should be interpreted with caution. Future research with longitudinal designs is needed to clarify the direction and mechanisms of these associations. Educational programs that incorporate smartphone use, eating habits, physical appearance, and physical activity are proposed for future evaluation rather than recommended on the basis of these findings.