Weight stigma questionnaire : The development and validation of a weight stigma measure for use in adults

Weight stigma is pervasive and is associated with numerous negative consequences for biopsychosocial health and well-being. To study weight stigma, researchers have utilised the available measures intended to assess this phenomenon, and the number of weight stigma measures available is growing. The main objective of this research project was to assess the psychometric evidence of existing weight stigma measures for adults and use the findings of this research, along with a social psychology understanding of stigma, to inform the development of a new measure. I sought to achieve this across four studies. The first study was a systematic literature review and evaluation of the psychometric properties of every existing measure of weight stigma in adults. This review found that structural validity, internal consistency, and hypothesis testing were the most frequently assessed and reported psychometric properties, but evidence for content validity, cross-cultural validity, reliability, measurement error, criterion validity, and responsiveness were lacking in assessment/reporting. Additionally, the commonly discussed types of weight stigma (experienced, perceived, internalised) have not been carefully considered or represented in item development. In response to the findings of the review, the remaining studies report on the development and validation of a new weight stigma measure. Study 2 reports the item development and content validity assessment across four phases: (1) item development informed by theoretical and empirical literature, (2) item review by internal researchers assessing item relevance and comprehensiveness, (3) a Delphi Study with research experts assessing item relevance and comprehensiveness, and (4) a Cognitive Interview study with individuals from the community assessing item relevance, comprehensibility, and comprehensiveness. Experts and community members reviewed the scale in two rounds. Overall, consensus was achieved by all experts and community members, favouring inclusion of most of the items, after modification of item wording across rounds. The final number of items was 101. The next two studies involved conduct of psychometric assessment on the 101 items. Study 3 employed exploratory factor analysis (EFA) to reduce this item pool and identify the factor structure underlying the items. In addition to this, the scale’s internal consistency, reliability, and concurrent and known-groups validity was assessed. Participants (n = 999) included a sample of adults (aged 18-65) across the weight spectrum. The EFA identified six subscales in the final Weight Stigma Questionnaire (WeSQ): Perceived, Internalised, Functional self-stigma, Experienced, Healthcare, and Intimate Relationships subscales. The WeSQ and its subscales demonstrated excellent internal consistency (all α’s >.90) and test-retest reliability (all ICC’s > .90). Furthermore, the WeSQ and its subscales were (a) positively related to existing weight stigma measures (concurrent; all r’s > .56), and (b) related to weight, age, and gender in the expected direction. Finally, the goal of the fourth study was to confirm the factor structure of the scale and to gather evidence of convergent validity using a sample of adults (n = 614). The 6F structure was supported by confirmatory factor analysis (CFA), meeting criteria on all relevant fit indices (CFI = .994, RMSEA = .043; SRMR = .056). Convergent validity was demonstrated via correlations with maladaptive eating behaviour, intuitive eating responses, body appreciation, quality-of-life, and sports and physical anxiety in the expected direction (all .09 < /r/ < .80). The final WeSQ is the first weight stigma measure to demonstrate satisfactory evidence of all psychometric properties. The WeSQ is suitable for use in clinical and research studies that aim to (1) explore the broad range of stigma experiences related to weight (of any weight) both across subscales or in specific subscales (using individual subscales only), (2) evaluate the impact, and/or possible risk factors associated with weight stigma, and (3) determine how the stigma types differentially relate to and predict biopsychosocial consequences.