Psychometric properties of the Arabic versions of the Three-Item Short Form of the modified Weight Bias Internalization Scale (WBIS-3) and the Muscularity Bias Internalization Scale (MBIS).

Background: There is a lack of psychometrically sound measures to assess internalized weight and muscularity biases among Arabic-speaking people. To fill this gap, we sought to investigate the psychometric properties of Arabic translations of the Three-Item Short Form of the Modified Weight Bias Internalization Scale (WBIS-3) and the Muscularity Bias Internalization Scale (MBIS) in a sample of community adults.

Methods: A total of 402 Lebanese citizens and residents enrolled in this cross-sectional study (mean age: 24.46 years (SD = 6.60); 55.2% females). Exploratory Factor Analysis (EFA) was conducted using the principal-axis factoring and oblimin rotation to estimate parameters and the parallel analysis to determine the number of factors. CFA was conducted using the weighted least square mean and variance adjusted estimator which was recommended for ordinal CFA.

Results: An Exploratory Factor Analysis of the WBIS-3 resulted in a robust single-factor solution for the three items. An examination of the factorial structure of the MBIS revealed a two-factor structure, which showed adequate model fit. We obtained excellent internal consistency as indicated by McDonald's ω coefficients of .87 for the WBIS-3 total score and ranging between .92 and .95 for the MBIS two factor scores. Cross-sex invariance of the MBIS was confirmed at the configural, metric, and scalar levels. Convergent validity was supported by significant correlations between the WBIS-3 and MBIS. Divergent and concurrent validity were approved by showing small to medium correlations between MBIS/WBIS-3 scores and muscle dysmorphia, disordered eating symptoms, and body image concerns.

Conclusion: Findings suggest that the Arabic versions of the WBIS-3 and MBIS are suitable for use in Arabic-speaking adults.