Muscle dysmorphia among Brazilian gender-expansive individuals and transgender men: Factor structure and measurement invariance of the Muscle Dysmorphic Disorder Inventory (MDDI)

Muscle dysmorphia is a specifier of body dysmorphic disorder marked by a pathological need for muscularity and the obsession that one is either too small or not muscular enough. Most research on muscle dysmorphia has been done in cisgender men and there is a dearth of literature on the topic among gender-minoritized individuals. The present study aimed to determine whether the Muscle Dysmorphic Disorder Inventory (MDDI), one of the most used measures of muscle dysmorphia symptoms, exhibits good psychometric properties among Brazilian gender-expansive and transgender men. In the present study, we perform a psychometric evaluation of the Brazilian Portuguese translation of the MDDI in a sample of 157 gender-expansive and 137 transgender men. Confirmatory factor analysis supported the original 3-factor structure of the MDDI (i.e., drive for size, appearance intolerance, and functional impairment). The MDDI subscales were correlated with drive for muscularity and appearance-ideal internalization, confirming its convergent validity. Furthermore, good internal consistency and test-retest reliability were found. Results support the use of the MDDI in a sample of Brazilian gender-expansive individuals and transgender men, enabling the investigation of muscle dysmorphia and its correlates among Brazilian gender-minoritized individuals.