Orthorexia nervosa (ON) is characterized as obsessional healthy eating that results in malnutrition and/or psychosocial impairment. Yet, ON shares theoretical overlap with eating disorders (EDs), especially anorexia nervosa (AN), as well as obsessive-compulsive disorder (OCD). This study aimed to further understand ON and its overlap with related disorders by assessing the ability of ON for detecting the presence/absence of threshold ED, AN, and OCD symptoms.
An observational survey was completed by 197 participants recruited through eating disorder, dieting, and mental health support groups. Receiver operating characteristic (ROC) curve analyses determined the predictive ability of ON symptoms (assessed by Eating Habits Questionnaire [EHQ] orthorexia nervosa [OrNe] and healthy orthorexia [HeOr] subscales, and the Orthorexia Nervosa Inventory [ONI]) for detecting disordered eating symptoms (determined by Eating Disorder Examination Questionnaire [EDE-Q] global cut-scores), probable AN (determined by EDE-Q cut-scores and body mass index [BMI] <18.5), and OCD symptoms and obsessional thinking (assessed by the Revised Obsessive-Compulsive Inventory [OCI-R]).
Results showed both the ONI and EHQ OrNe measures are able to adequately predict ED symptoms and AN; however, both were poor to moderate at detecting OCD symptoms and obsessional thinking. Healthy orthorexia was poor to moderate at detecting outcomes.
These results suggest that ON, as it is currently operationalized, may be more closely related to EDs than OCD, and that ON may represent a subtype of AN. Results also support healthy orthorexia as a distinct construct to ON. While results are limited by the lack of definitive ON diagnostic criteria, findings suggest that treatments developed for EDs might be most suited to ON.
ON has been proposed as a psychiatric disorder, and it shares theoretical overlap with several existing disorders. This study adopts a novel approach to assessing and exploring the overlap of ON with EDs, AN and OCD. Results suggest that ON shares more overlap with EDs and might best be understood as a subtype of EDs or AN.