Evaluation of psychometric properties of the eating restriction questionnaire and food involvement inventory in Iranian adults.

The objectives of this study were to translate and validate the Persian version of the food involvement inventory (FII) and eating restriction questionnaire (ERQ) and to determine the measurement invariance based on gender, body mass index (BMI) status, and age. This cross-sectional study included 1100 Iranian adults. Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were used to evaluate the construct validity of FII and ERQ. Convergent and discriminant validity, measurement invariance in gender, BMI and age, reliability including internal consistency, and stability were investigated for FII and ERQ. The results showed that the four-factor construct of the FII and the one-factor construct of the ERQ were 44.27% and 55.12% of the total variance, respectively. The factor loadings of all items were > .3 in both scales and none of the items were deleted. Fitting indices indicated that the four-factor construct of the FII and the one-factor construct of the ERQ had a good and acceptable fit among the Iranian adults. The Persian versions of the FII and ERQ, translated into Persian and localized according to international standards, had high construct, convergent and discriminant validity as well as high reliability.