부산대학교 도서관

Introduction: Type 2 diabetes is a preventable condition. Ninety percent of diagnoses are attributable to lifestyle factors (physical activity/diet/overweight/obesity). Many psychological theories and models identify motivational and volitional determinants of health-related behaviour change, however, initiating and sustaining change is challenging. Aims: To explore the implementation of self-regulatory behaviour change techniques (BCTs), engagement levels, and associations with initial (6m) and longer-term weight-loss (24m). Design: The thesis comprised three studies which were undertaken within the context of a large diabetes prevention RCT. Results: The systematic review (n=20) showed that the HAPA model was rarely explicitly cited as the basis of interventions but, in a meta-analysis (n=7), 'HAPA-like' interventions that included volitional (self-regulatory) components, led to significant initial and longer-term weight losses. A primary study analysing longitudinal data observed significant increases in engagement in all self-regulatory strategies (action-planning, self-monitoring, problem-solving, coping-planning, and self-weighing) from baseline to 24 months, however declines were observed between 12-24 months in action planning, coping planning and frequency of self-weighing. All self-regulatory strategies were significant predictors of initial and longer-term weight-loss amongst intervention participants, with those reporting higher self-regulatory engagement, showing the greatest weight losses. In a final study, action-plan data (n=1900), explored how participants engaged in action-planning within a "real-world" intervention. Participants set an average of two action-plans per worksheet, but the number declined as the intervention progressed. Out of a possibly score of four (representing What/Where/When/Who), the average specificity of action-plans was two. Specificity decreased as the number of action-plans set increased. The number of action-plans set was statistically significantly associated with weight-loss, but specificity was not. Conclusion: This thesis provides further support for the inclusion of self-regulatory strategies within weight-loss interventions and recommends, prompting engagement in self-regulatory strategies after 12-months, implementing coping-planning for both initial and longer-term weight-loss, and setting multiple action-plans. Further research should explore participant engagement and utility of other BCTs in "real-life" programmes.