Habitual behaviour and weight control

With obesity rates rising steadily in most parts of the world, there is considerable interest in novel weight loss interventions. This thesis tests the utility of habit formation theory for designing behaviour change advice for weight loss. Central to models of habit operation is the idea that habits develop through repetition of the behaviour in consistent contexts (Context Dependent Repetition CDR), but the process itself has attracted little research attention, and it has never been used as a basis for interventions. This thesis used CDR as the basis of a weight loss intervention and also examined the process of habit development for diet and activity behaviours. Study 1 was an eight week pilot study with ten participants who were given simple advice on developing diet and exercise habits associated with weight loss. Post-intervention interviews found evidence that some behaviours had acquired 'automaticity' - the hallmark of habits - and weight data showed an average 3kg weight loss. Study 2 extended the evaluation of the intervention in a randomised controlled trial of the habit-based advice compared with a no-treatment control group, incorporating standardised measures of automaticity. The results showed significantly greater weight loss in the intervention group, which was maintained over follow up. The recommended behaviours also became increasingly automatic. Study 3 tracked changes in automaticity over three months as volunteers repeated one eating or activity behaviour in a consistent context on a daily basis. The results showed that advice on CDR is sufficient to promote habit formation and supported the prediction that an asymptotic curve of increasing automaticity reflects a generalised habit-formation process. The average length of time to reach an asymptote was 70 days. This research has contributed to the understanding of habit formation and shown that it may be a useful foundation for simple, easily disseminable, weight loss interventions