Development and initial psychometric evaluation of the Body Image Matrix of Thinness and Muscularity – Female Bodies

BACKGROUND: Despite evidence that thinness and muscularity are part of the female body ideal, there is not yet a reliable figure rating scale measuring the body image of women which includes both of these dimensions. To overcome this shortcoming, the Body Image Matrix of Thinness and Muscularity - Female Bodies (BIMTM-FB) was developed. METHODS: The objective of this study is to analyze the psychometric properties of this measure. N = 607 non-clinical women and N = 32 women with eating disorders answered the BIMTM-FB as well as instruments assessing eating disorder symptoms and body image disturbance in order to test the convergent validity of the BIMTM-FB. To assess test-retest reliability, a two-week interval was determined. RESULTS: The results indicated that the body-fat dimension of the BIMTM-FB correlates significantly with the Contour Drawing Rating-Scale, the Drive for Leanness Scale (DLS) and the Body Appreciation Scale, while the muscularity dimension of the BIMTM-FB was significantly associated with the DLS and the Drive for Muscularity Scale, proving the convergent validity of the BIMTM-FB. High coefficients of test-retest reliability were found. Moreover, the BIMTM-FB differentiated between the clinical sample and the non-clinical controls. CONCLUSIONS: The BIMTM-FB is a figure rating scale assessing both thinness and muscularity as part of the female body ideal. Due to its high reliability and validity, the BIMTM-FB can be recommended in research and practice. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s40337-020-00345-w.