The Pathological Pursuit of Muscularity: Improving Understanding of the Phenomenology and Treatment of Muscle Dysmorphia

Abstract

Muscle dysmorphia (MD) is a psychological disorder characterised by extreme preoccupation that one is not big or muscular enough, rigid diet and exercise practices, and significant functional impairment. To date, little research has explored the lived experience of MD and potential treatments. The overarching aim of this thesis was to better understand the phenomenology of MD and use this knowledge to develop and evaluate a novel psychotherapy intervention for MD. This thesis consists of six chapters, including four chapters containing empirical studies. Chapter 2 is a published systematic review and meta-analysis of treatments for compulsive exercise in MD and eating disorders, a closely related illness group. We found that interventions in eating disorders produced small effects vs. control groups, but that there were no studies in MD, a glaring gap in the literature. Chapter 3 consists of two published qualitative articles that explored the phenomenology of muscle dysmorphia in 29 adults with diagnosed MD. Using reflexive thematic analysis, we identified a range of themes that capture the lived experience of MD. Chapter 4 is a published article presenting questionnaire scores on six psychometrically validated and clinically relevant questionnaires to MD, which we compared to those reported in past studies to build the base of questionnaire data in the literature on adults with diagnosed MD. Chapter 5 is a pilot and feasibility study of an eight-week telehealth cognitive-behavioural therapy (CBT) program currently under peer review. We found high acceptability and feasibility of the program, as well as significant, large improvements from pre- to post-treatment in core measures assessing MD symptoms, compulsive exercise, and disordered eating. All treatment improvements were maintained at three-month follow up. Findings from this thesis have improved comprehension of the lived experience of MD and the preliminary efficacy and acceptability of CBT interventions.