Exploration of the Diagnostic Classification of Orthorexia Nervosa: Distinct Disorder, Anorexia Nervosa or Obsessive-Compulsive Disorder?

Abstract PurposeOrthorexia Nervosa (ON) is characterised as obsessional healthy eating that results in malnutrition and/or psychosocial impairment. Yet, its diagnostic classification remains uncertain, with theoretical overlap with Anorexia Nervosa (AN) and Obsessive-Compulsive Disorder (OCD). This study aimed to further understand appropriate diagnostic classification by assessing the ability of ON for detecting the presence/absence of AN and OCD.MethodAn observational survey was completed by 362 participants recruited through eating-disorder, dieting and mental health support groups. Receiver Operating Characteristics (ROC) curve analyses determined the predictive ability of ON symptoms (assessed by ORTO-15 and ORTO-9) for detecting AN (determined by EAT-26 cut-scores and BMI >17.5), and OCD and Obsessional thinking (assessed by the OCI-R).ResultsResults showed both ON measures are able to adequately predict AN, however ON was poor to moderate at detecting OCD and Obsessional thinking. Specificity for detecting AN was poor and ability to discriminate between AN and ON was low.ConclusionThese results suggest that ON, as it is currently measured, may be more closely related to EDs than OCD, and that ON may represent a subtype or subset of AN; although results are limited by the lack of definitive ON diagnostic criteria and limitations of ON measures.Level of evidence – Level V, cross-sectional descriptive study