A Mixed-Methods Exploration of Atypical Eating Behaviours in Obsessive-Compulsive Disorder

Obsessive-compulsive disorder (OCD) is a debilitating mental health condition that has a significant impact on daily functioning, with this impact potentially extending to eating behaviours. However, the current literature base presents a limited understanding of eating patterns amongst individuals with OCD. This limited understanding poses a concern, as OCD is often seen as a risk factor for both eating disorders and physical health issues. To address these gaps in understanding, the current thesis had two key aims: first, to examine atypical eating behaviours among adults with OCD and/or obsessivecompulsive (OC) symptoms; and second, to explore the underlying factors that may contribute towards atypical eating behaviours in this population. The exploration of atypical eating behaviours encompassed not only eating disorders but also subclinical eating patterns, such as selective eating (i.e., food fussiness), which do not meet the diagnostic threshold for an eating disorder. The thesis adopted a mixed methods design to gain a comprehensive overview of atypical eating behaviours in those with OCD and/or OC symptoms. An initial scoping review was conducted to understand the extent of current scientific knowledge on atypical eating behaviours in this population. Gaps in knowledge were then used to formulate the empirical studies of the thesis, which were undertaken in two parts. Section I examined atypical eating behaviours among adults with elevated OC symptoms in the general population, while Section II focused specifically on individuals with a diagnosis of OCD, drawing on the perspectives of those with a lived experience, as well as healthcare professionals. The studies of Section I utilised self-report questionnaires, whereas Section II adopted both self-report questionnaires and semi-structured interviews. Findings from the current thesis revealed that adults diagnosed with OCD, as well as individuals in the general population with elevated OC symptoms, frequently engage in atypical eating behaviours that vary in both type and severity. Among adults in the general population who exhibit greater OC symptomatology, atypical eating behaviours appeared to be underpinned by factors such as perfectionism, emotion regulation and sensory sensitivity. However, for those with OCD, the relationship between atypical eating and OC symptoms was more complicated and affected by specific OC symptoms (e.g., contamination), characteristics of OCD (e.g., harm avoidance), transdiagnostic factors and co-occurring disorders, such as autism spectrum disorder and eating disorders. Despite atypical eating behaviours posing significant impairments to daily functioning, individuals with OCD and healthcare professionals reported barriers in accessing treatment for them. The thesis findings highlight the need to acknowledge that individuals with OCD and/or OC symptoms may experience significant challenges with their eating behaviours. It is of vital importance to address these issues in clinical practice to reduce the complex psychological and physical burden posed by atypical eating.