Psychometric Properties of Persian Version of the Orthorexia Nervosa Scale (ONS)

Adopting a balanced diet promotes human health. However, excessive focus on healthy eating can lead to food obsession, which is termed orthorexia nervosa (ON). The aim of this study was to determine the psychometric properties of the Persian version of the Orthorexia Nervosa Scale (ONS).

The statistical population of this study consisted of all undergraduate students of the Islamic Azad University, Tehran Science and Research Branch in the academic year 98-99, among whom 322 students (201 females, 121 males) were selected by multistage sampling, and they responded to the Orthorexia Nervosa Scale (ONS), the Eating Attitude Test (EAT-26), the Obsessive-Compulsive Inventory (OCI-R), the Multidimensional Perfectionism Scale (MPS), the Body    Image-Acceptance and Action Questionnaire (BI-AAQ), and the NEO Five Factor Inventory (NEO-FFI). The data were analyzed by exploratory factor analysis, confirmatory factor analysis, Cronbach’s alpha and Pearson correlation using SPSS and AMOS.

Results of the exploratory factor analysis showed 2 factors with eigenvalues higher than 1 which explained 41/92% of the total variance. Also, confirmatory factor analysis indicators implied the optimal fitness of  two-factor model of this scale. The total reliability of the scale was estimated to be respectively 0.78 and 0.81 using Cronbach’s alpha and split half. Convergent validity and divergent validity were also confirmed by calculating scale correlation through the aforementioned scales (p<0.05). Also, this scale had a positive and significant correlation with neuroticism (p<0.01).

The Orthorexia Nervosa Scale has a relatively proper validity and reliability for being used in Iranian samples and can be a suitable tool for researches of this field.