Abstract
Research has identified weight bias and weight bias internalisation (WBI) as key consequences of obesity. To date, however, the conceptualisation, operationalisation and causes of these constructs lacks clarity. Framed within sociocultural theory, with a focus on the role of friendship, family, and the media this multi-methods thesis broadly aimed to explore the role of sociocultural factors on body weight, weight bias and health behaviours through a systematic review and four empirical studies. Firstly, the systematic review (N=15 studies) explored the role of friends on body weight. This provided evidence that friends can influence body weight but indicated that further research is needed to understand the mechanisms behind this relationship. Study 1 presented a conceptual evaluation of measures of weight bias and WBI using a card-sort methodology (N=357). Findings suggested that whilst measures of WBI match the conceptualisation of this construct, measures of weight bias are more problematic focusing on causes of obesity alongside negative beliefs. A new amalgamated measure of weight bias is therefore presented to reflect the conceptualisation of this construct as focusing on negative beliefs. Using this new measure, Study 2 used a cross-sectional methodology to explore the role of social exposure in predicting weight bias and WBI in an international sample (N=1,026) and highlighted the importance of personal level (rather than population level) social exposure in predicting weight bias and WBI. Study 3 addressed the role of exposure through the media and using an experimental design investigated the impact of media imagery (body diversity vs. thin-idealistic) on weight beliefs and health outcomes in women (N=160). This suggested that whilst exposure to body diversity imagery reduced weight bias, exposure to thin-ideal messaging increased healthy eating intentions. Finally, Study 4 used qualitative methods to explore how those with overweight and obesity (N=10) responded to media messaging concerning the relationship between obesity and COVID-19. Findings suggested that whilst this messaging was motivating for some, others perceived it to be stigmatising. Overall, findings from this thesis suggest that sociocultural factors influence body weight, weight bias and health behaviour. Further, the results indicate that social exposure via processes such as social contagion and normalisation is an active process, in which individuals actively engage with the norms around them, rather than being passively influenced by them.