Weight Bias Internalization Scale: Psychometric Properties and Population Norms

OBJECTIVE: Internalizing the pervasive weight bias commonly directed towards individuals with overweight and obesity, co-occurs with increased psychopathology and impaired quality of life. This study sought to establish population norms and psychometric properties of the most widely used self-report questionnaire, the Weight Bias Internalization Scale (WBIS), in a representative community sample. DESIGN AND METHODS: In a survey of the German population, N = 1158 individuals with overweight and obesity were assessed with the WBIS and self-report measures for convergent validation. RESULTS: Item analysis revealed favorable item-total correlation of all but one WBIS item. With this item removed, item homogeneity and internal consistency were excellent. The one-factor structure of the WBIS was confirmed using confirmatory factor analysis. Convergent validity was shown through significant associations with measures of depressive and somatoform symptoms. The WBIS contributed to the explanation of variance in depressive and somatoform symptoms over and above body mass index. Higher WBIS scores were found in women than in men, in individuals with obesity than in individuals with overweight, and in those with lower education or income than those with higher education or income. Sex-specific norms were provided. CONCLUSIONS: The results showed good psychometric properties of the WBIS after removal of one item. Future research is warranted on further indicators of reliability and validity, for example, retest reliability, sensitivity to change, and prognostic validity.