Validity and reliability of the Arabic orthorexia nervosa inventory scale in young adults: a validation study

Purpose This study aimed to translate and validate the Arabic version of the Orthorexia Nervosa Inventory (ONI) scale to assess orthorexia nervosa (OrNe) among young Arabic-speaking adults in the UAE and explore the relationship between OrNe and various sociodemographic factors. Methods A total of 625 young adult participants (88.2% female) completed a questionnaire comprising the ONI scale and sociodemographic questions. The study assessed internal reliability using Cronbach’s α, external reliability using intraclass correlation coefficient (ICC), content validity using a panel of 12 experts, Known-Group validity using associations between OrNe classification and demographics, and structural validity using confirmatory factor analysis. Results The Arabic ONI scale showed high internal (Cronbach’s α = 0.934) and external (ICC = 0.849) reliability. Content validity was excellent (scale-level content validity index = 0.96). Vegetarians had significantly higher ONI scores, indicating good Known-Group validity. The model fit indices (χ2/df = 1.663, comparative fit index = 0.993, Tucker–Lewis index = 0.992, goodness-of-fit index = 0.989, root mean square error of approximation = 0.033, standardized root mean square residual = 0.049) reflected excellent structural validity. Conclusions The Arabic ONI scale is a reliable and valid tool for assessing OrNe tendencies in young Arabic-speaking adults. Future studies should explore its applicability to broader populations and investigate predictors of OrNe tendencies. Level of evidence Level V, descriptive cross-sectional study.