Weight bias is defined as negative attitudes towards, and beliefs about, others because of their weight. Like other forms of stigma, weight stigma has a harmful impact on health, including depressive symptoms, disordered eating, body image disturbances and poor quality of life. Several instruments measuring weight-related attitudes have been developed, such as the Attitudes Toward Obese Persons (ATOP). The purpose of this study was to test the psychometric properties of the Italian version of the ATOP (I-ATOP).

The ATOP was adapted into Italian following the back-translation procedure. A total of 800 participants (M_age=31.40; 54.9% females) completed the I-ATOP alongside the Weight Bias Internalization Scale (WBIS). Exploratory factor analysis (EFA) was conducted on half of the sample, while the remaining half was selected to cross-validate the resulting solution via confirmatory factor analysis (CFA). Factorial invariance tests across gender were computed using multi-group CFA.

EFA suggested a one-factor structure with four items excluded due to their low standardised loadings. The trimmed model was cross-validated showing an acceptable fit to the data: MLRχ2 = 159.467 (df=81); RMSEA= 0.049; CFI= 0.939; TLI= 0.910; SRMR= 0.046. An omega coefficient of 0.818 confirmed the strong reliability of the I-ATOP. Convergent validity was demonstrated by a significant and moderate correlation with the WBIS. Configural, metric, and scalar invariance across gender were established.

I-ATOP demonstrated to be a valid and reliable instrument useful for both clinical and research practices, as well as to support the development of educational and therapeutic actions able to reduce the stigma among the general public.