Psychometric validation of the fit body scale for assessing muscularity related body dissatisfaction in Iranian adults

The Fit Body Scale is a newly developed scale that measures body dissatisfaction with muscularity ideals. It has gender-specific versions, the Female Fit Body Scale (FFITBS) and the Male Fit Body Scale (MFBS). The current study examined the psychometric properties of the Fit Body Scale in Iranian women and men. A total of 667 females and 226 males from the Iranian population completed a battery of tools, including FFITBS, MFBS, Drive for Muscularity Scale (DMS), Eating Attitude Test (EAT-26), Body Appreciation Scale (BAS), and Yale-Brown modified Obsessive-Compulsive Scale for Body Dysmorphic Disorder (YBOCS-BDD). We examined the 2-week test-retest reliability, and the results showed a satisfactory Intraclass Correlation Coefficient (ICC) for both FFITBS and MFBS. For both genders, relationships between body mass index (BMI) and current body shape selected by participants from nine body shapes in the FFITBS and MFBS were positive, demonstrating the scales’ concurrent validity. In addition, the correlations of DMS with FFITBS and MFBS were positive, indicating convergent validity. The correlation between EAT-26 and FFITBS was significant, but its correlation with MFBS was insignificant. The significant negative correlation between BAS and FFITBS indicates divergent validity of FFITBS, but no correlations were found with MFBS. The study results suggest that the FFITBS and MFBS are psychometrically valid tools for measuring body dissatisfaction regarding the muscularity ideal among the Iranian population.