Orthorexia nervosa: examining the Eating Habits Questionnaire's reliability and validity, and its links to dietary adequacy among adult women.

OBJECTIVE: There has been increasing interest in identifying individuals with pathological healthy eating behaviours, or orthorexia nervosa (ON). This study aimed to investigate the validity (construct- and criterion-related) and reliability (internal consistency) of the Eating Habits Questionnaire (EHQ) as a measure of ON. A secondary aim was to examine how the EHQ would predict a distinct feature of ON, adequate dietary intake. DESIGN: Cross-sectional online questionnaire incorporating existing measures of ON and dietary intake. SETTING: Participants were recruited online via social media and a university's research webpage. PARTICIPANTS: Women (n 286) ranging in age from 17 to 73 years. RESULTS: Exploratory factor analysis established that the EHQ represented four ON dimensions (Healthy Eating Cognitions, Dietary Restriction, Diet Superiority and Social Impairment), inconsistent with the scale's original three dimensions (Problems, Knowledge and Feelings). Cronbach's α coefficients ranged from 0·72 to 0·80 for the four subscales and was 0·89 for the total EHQ scale. Criterion-related validity revealed a significant moderate to strong correlation (r = -0·54, P < 0·001) between the EHQ and ORTO-10 (a ten-item version of ORTO-15). The EHQ, particularly the EHQ-Diet superiority subscale, was found to be predictive of better, as opposed to, poorer dietary adequacy. CONCLUSIONS: Findings suggest that improvements still need to be made to the EHQ for it to be a valid and reliable measure of ON. Ideally, new assessment tools based on established diagnostic criteria are needed to advance our understanding of ON.