Further evaluation of the psychometric properties of the German version of the Body Appreciation Scale-2 (BAS-2): Cross-validation, measurement invariance, and population-based norms.

Using a representative sample of the German general population (N = 2509, 16-74 years), this work aimed to cross-validate the modified one-factor model recently reported for the German Body Appreciation Scale 2 (BAS-2). We also examined measurement invariance across gender, tested differential item functioning across age and BMI, systematically evaluated subgroup differences, and provided norms according to subgroups. Overall, the BAS-2 demonstrates good internal consistency. Cross-validation supported the generalizability of the modified one-factor model. Multi-group confirmatory factor analyses supported full scalar invariance across gender; comparisons revealed higher scores among men compared to women with a small effect size. Age (only women) and BMI (both genders) significantly predicted latent BAS-2 scores. Of note, differential item functioning for age and BMI was observed. Concerning manifest group differences, we found a significant main effect of weight status: Individuals with obesity reported the lowest body appreciation levels, while individuals with underweight/ normal weight reported highest levels. Our findings suggest that the German BAS-2 has good psychometric properties and is suitable for examining body appreciation across gender among German women and men. Moreover, norm values enable future usage of the scale in health and clinical research by providing reference data for interpretation.