Adaptation of the orthorexia beliefs scale into Turkish: a validity and reliability study

Orthorexia nervosa is characterized by an excessive preoccupation with healthy eating, rigid dietary rules, and dysfunctional beliefs related to food, health, morality, and control. Despite the growing interest in orthorexia research in Türkiye, instruments directly assessing orthorexic beliefs remain limited. This study aimed to adapt the Orthorexia Beliefs Scale into Turkish and evaluate its psychometric properties in a sample of healthy adults.

This methodological study was conducted between October 2025 and January 2026 using an online snowball sampling strategy. The adaptation process followed a standard forward-backward translation procedure. A pilot study was first performed to assess item clarity and preliminary reliability (n = 210). Subsequently, the main study included 1,652 participants, with separate samples allocated for exploratory factor analysis (EFA; n = 700) and confirmatory factor analysis (CFA; n = 952). Participants completed the OBS, Teruel Orthorexia Scale (TOS), Eating Attitudes Test-26 (EAT-26), Obsessive-Compulsive Inventory-Revised (OCI-R), and Positive and Negative Affect Schedule (PANAS). Internal consistency, construct validity, convergent validity, and criterion validity were evaluated.

The Kaiser-Meyer-Olkin value (0.922) and significant Bartlett's test of sphericity (χ² = 8,144.004, p < 0.001) confirmed sample adequacy for factor analysis. EFA supported a three-factor structure-Overvaluation of Healthy Eating, Need for Control, and Moral Meaning-explaining 53.997% of the total variance. CFA demonstrated good model fit (χ²/df = 3.085, RMSEA = 0.047, CFI = 0.981, NFI = 0.972, SRMR = 0.059, GFI = 0.983, AGFI = 0.979). The total scale showed excellent internal consistency (McDonald's Omega = 0.922). Standardized factor loadings, composite reliability, and average variance extracted values supported convergent validity. OBS total scores were positively associated with orthorexia-related behaviors, obsessive-compulsive symptoms, and affective measures, supporting criterion validity.

The findings indicate that the Turkish version of the Orthorexia Beliefs Scale is a valid, reliable, and culturally appropriate instrument for assessing orthorexic beliefs in the Turkish population and may contribute to future clinical and cross-cultural research on orthorexia nervosa.