Grazing in Obesity and Eating Disorders: Prevalence, Clinical Correlates and Relationships with Executive Functioning and Goal-Directed Behaviour

Abstract

Grazing is a common, detrimental eating behaviour in bariatric surgery settings. Little is known about grazing in obesity in general, or within eating disorders. The aim of this thesis was to improve understanding of the prevalence and clinical correlates of grazing within obesity and eating disorders, and associations with other relevant factors such as quality of life and cognitive functioning. This thesis reports a series of studies designed to address gaps in the literature, including a systematic review and meta-analysis of prevalence, a validation study for a brief instrument (Short Inventory of Grazing; SIG), a general population survey using the SIG, and three other empirical studies investigating links between grazing, executive functioning and goal-directed behaviour. Overall, grazing, especially compulsive grazing (incorporating a strong sense of loss of control), was found to be widely prevalent within obesity and binge-type eating disorders, and it was associated with high weight, more severe eating disorder symptomatology and lower mental-health related quality of life. It was also found that obesity was associated with lower performance across some executive functions, and that persons with obesity and eating disorder symptoms were less likely to perform behaviour that was goal-directed. However, both executive functioning and goal-directed behavioural performance had small positive associations with grazing. Furthermore, differences in executive functioning and goal-directed behaviour were not found to mediate severity of grazing behaviour, suggesting a more complex relationship between these variables. In conclusion, grazing, especially when compulsive, represents a clinically-significant eating pattern which should be taken into consideration in the assessment and treatment of obesity and eating disorders.