Orthorexia nervosa and exercise addiction: distinct entities beyond restrictive and muscularity-oriented disordered...

Orthorexia Nervosa (OrNe) and Exercise Addiction (EA) are potentially dysfunctional variants of health-oriented behaviours, but their status as distinct mental disorders remains debated. OrNe is the obsessive preoccupation with 'healthy' eating, whereas EA is characterized by loss of control over exercise and prioritization over other life domains. Both commonly coincide with disordered eating, raising the question whether the clinical indicators are inherent to OrNe and EA or primarily reflect overlapping eating pathologies. This study examined whether OrNe and EA are distinct from restrictive and muscularity-oriented disordered eating by assessing their overlap and their unique links to psychological distress and psychosocial impairment.

Within a cross-sectional web-based study, 384 participants (age = 31.5±11.5; 76.3% women) completed the Teruel Orthorexia Scale (TOS), Exercise Dependence Scale Revised (EDS-R), Eating Disorder Examination-Questionnaire (EDE-Q), Muscularity-Oriented Eating Test (MOET), Brief Symptom Inventory-18 (BSI-18), and Clinical Impairment Assessment Questionnaire (CIA).

Bivariate correlation analyses revealed strong overlaps of TOS-OrNe with both forms of disordered eating (EDE-Q: r = .635, MOET: r = .730), which were significantly more pronounced in women (EDE-Q: r = .676, MOET: r = .810) than men. EA was strongly correlated with MOET (r = .536), and weakly with EDE-Q (r = .242). Multiple regression and path analyses showed OrNe predicted psychosocial impairment and psychological distress both directly and mediated by EDE-Q, whereas EA was not uniquely linked to clinical indicators. Exploratory factor analysis further suggested strongly related latent constructs.

Although OrNe was uniquely associated with psychological distress and impairment, its substantial overlap with restrictive and muscularity-oriented disordered eating challenges its validity as a distinct disorder. EA's association with impairment appears largely explained by muscularity concerns, questioning its conceptualization as a behavioural addiction. These findings underscore the importance of considering muscularity-related motives and behaviours in both research and clinical assessment. Overall, OrNe and EA may reflect socioculturally shaped expressions of disordered eating rather than independent mental disorders.