Measurement invariance and psychometric properties of three positive body image measures among cisgender sexual minority and heterosexual women.

Positive body image is a multidimensional construct consisting of various facets including body appreciation, body image flexibility, and functionality appreciation measured via the Body Appreciation Scale-2 (BAS-2), Body Image-Acceptance and Action Questionnaire-5 (BI-AAQ-5), and Functionality Appreciation Scale (FAS), respectively. Research has supported the unidimensional factor structure of these measures; however, invariance testing based on sexual identity has yet to be conducted. The study's primary aim was to assess the measurement invariance of the BAS-2, BI-AAQ-5, and FAS between sexual minority and heterosexual women. The secondary aim was to assess the psychometric properties of each positive body image measure among each sample. Participants were predominantly White, cisgender women who identified as a sexual minority (n = 310) or heterosexual (n = 360) and completed online questionnaires of positive body image, eating behaviors, and mental and physical health. Results supported invariance with no differences in BAS-2 or BI-AAQ-5 scores. A significant difference with a small effect size was found in FAS scores, with sexual minority women reporting lower FAS scores. Findings supported the BI-AAQ-5 and FAS's incremental validity on perceived mental health. Overall, results suggest that the BAS-2, BI-AAQ-5, and FAS scores can be compared among women of varying sexual identities.