Investigating and measuring knowledge and beliefs for successful weight loss maintenance

Obesity levels have increased in the past years and while there are effective interventions for weight loss, weight loss maintenance is more difficult to achieve. This thesis aimed to investigate whether knowledge and beliefs influence weight loss maintenance success. To this aim, a novel Weight Loss Maintenance Knowledge and Beliefs scale was developed and validated over a series of four studies. The necessity and importance of such a scale were explored focusing on theory, empirical evidence, and existing scales. A multi-dimensional scale was proposed consisting of two subscales: the Knowledge subscale which assesses knowledge about food choice and energy balance, and the Beliefs subscale that measures beliefs about hunger, calorie compensatory behaviours, and diet/obesity. In Study 1 the interpretation and understanding of the items was assessed in a sample from the general population (n = 16) using the ‘think aloud’ method. In Study 2, the factor structure, construct and face validity of the scale were analysed in a sample of nutrition (n = 106) and non-nutrition students (n = 302). The convergent, discriminant and predictive validity of the scale were evaluated in Studies 3 and 4 in samples of individuals attempting to manage their weight (n = 166), and weight loss maintainers and regainers (n = 238). In Study 4, the influence of knowledge and beliefs on the impact of the COVID-19 lockdown on weight management practices was investigated in a sample of individuals attempting to manage their weight when the first COVID-19 lockdown started. Overall, the results provided evidence of the reliability and validity of the new Weight Loss Maintenance Knowledge and Beliefs scale in a range of different samples. Scores on the scale were related to better weight maintenance, engagement in weight management attempts and physical activity. Initial evidence of the influence of knowledge and beliefs on weight loss maintenance was demonstrated. Implications of the current research and uses for the novel scale are discussed and future research directions are proposed.