From a healthy diet to pathology: exploring the complexity of orthorexia nervosa

Orthorexia Nervosa (ON) is described as a pathological obsession with 'healthy' eating. Its status as a clinical diagnosis is yet to be established with no consensus on diagnostic features or tools. This thesis' aim was to explore ON and understand its contributing dimensions. Results of this work, which included seven studies, highlight discrepancies with the existing diagnostic criteria and present a new independent measure of ON. Qualitative explorations of existing tool of ON (ORTO-15) (chapter 2) and in-depth interviews (chapter 3) suggest a great variability in reasons for adhering to the diet perceived as healthy. Commonalities cited included the desire to improve one's appearance and the desire for control over one's dietary intake. Unlike previous research, this work suggests considering appearance as important contributor to orthorexic tendencies. Exploration of nutritional composition of dietary intakes (chapter 3) further suggested that ON, unlike established eating disorders, is not characterised by malnutrition or any one pattern of nutritional deficiency. Individuals that claim their diets to be healthy demonstrated deficiency of several nutrients. The concept of a ‟healthy” diet is an individually prescribed concept that was not based on nutritional guidelines. Results of nutritional and qualitative explorations informed the development of an independent measure of ON (chapter 4). Screening Tool for Orthorexia Nervosa (STONE) and its short version (STONE-S) consider ON to comprise three dimensions: desire to enhance/maintain one's appearance, pure diet, and control over food consumption and preparation. STONE-S was a stronger tool able to differentiate ON from eating disorders, religious diets, restricted eating cause by medical conditions, and no restriction groups. Overall, the new measure could be a good starting point for exploring ON, and by shifting to a qualitative and nutritional perspectives, this thesis paints a more accurate picture of the features of this complex condition.