The muscle dysmorphia–eating disorders link as a public health concern: an epidemiological study of symptom dimensions and social isolation

Background: Eating disorders (EDs) represent a growing public health concern among university students, who face critical developmental transitions and increasing pressure from "fitness culture." This study examined the complex relationship between muscle dysmorphia (MD) symptomatology and ED risk, analyzing how specific psychopathological dimensions interact with socio-demographic variables and lifestyles. Methods: A cross-sectional study was conducted on a sample of 2,001 students from University of Catania using a web-based survey. The primary outcome was the risk of disordered eating attitudes, assessed via the Eating Attitudes Test-26 (EAT-26). The main explanatory variable was MD symptomatology, measured using the Muscle Dysmorphia Disorder Inventory (MDDI), analyzed both as a cumulative clinical risk (score >39) and through its specific subscales: Drive for size (DFS), Appearance intolerance (AI), and Functional impairment (FI). Multivariable logistic regression models were fitted to identify independent predictors. Results: The presence of clinical MD symptoms was identified as one of the strongest independent predictors of ED risk (OR = 2.94; 95% CI: 2.03-4.25). A sensitivity analysis on the MDDI subscales revealed divergent pathways: AI (OR = 1.18; 95% CI: 1.14-1.23) and FI (OR = 1.22; 95% CI: 1.17-1.28) were positive drivers of eating risk, whereas DFS showed a significant inverse association (OR = 0.93; 95% CI: 0.89-0.96). Sociodemographic analysis indicated that students aged 18-23, those living alone, and those who preferred not to disclose their gender (OR = 2.07; 95% CI: 1.15-3.73) were at significantly higher risk. Conversely, living with a partner (OR = 0.24; 95% CI: 0.13-0.42) or parents (OR = 0.39; 95% CI: 0.28-0.54) offered robust protection. Regarding lifestyle, intense sports practice was associated with a higher risk of EDs (OR = 1.50; 95% CI: 1.19-1.90). Conclusion: The findings confirm that MD symptomatology acts as a specific "gateway" to disordered eating but highlights a crucial distinction: the risk is driven by body image intolerance and social impairment rather than the ambition for muscle growth itself, which may be protective. These results suggest that university prevention strategies should focus on vulnerable phenotypes-specifically younger students, those socially isolated, and gender minorities-and screen for the distress accompanying fitness goals rather than the athletic discipline itself.