|dc.description.abstract||Discussions around the construct of ‘Orthorexia Nervosa’ (ON) have challenged perceptions of healthy diets and lifestyles, as well as assumptions about core characteristics of eating disorder (ED) symptoms. As a potential new clinical picture, ON describes an obsessive preoccupation with healthy eating which leads to physical as well as psychosocial impairments. In its original definition, ON was described as a unique ED, which involves extreme beliefs about foods’ health-promoting and health-damaging properties, rather than weight loss motivations or body image concerns. However, ON is not officially recognized as a disorder and its specific components are still disputed. The present thesis aimed to explore the conceptualisation of ON in the context of research, clinical practice, and within the general population. Four studies were designed to investigate how current understanding of ON relate to disordered eating, specific dietary choices, and general sociocultural developments.
First, a systematic review was conducted to evaluate the psychometric properties of all published ON assessment tools and to explore the variety of ON conceptualisations within current research. In total, ten ON assessment scales were identified and 68 unique studies were included in the narrative review, of which 40 studies were eligible for a reliability generalization analysis. By systematically evaluating available ON scales, conceptual inconsistencies were exposed, and limitations of published research findings were highlighted. Importantly, the most commonly used ON assessment tool (the ORTO-15) showed not only poor face validity, but also inconsistent and unsatisfactory psychometric properties across studies. In addition, culture-specific conceptualisations of ON were identified which challenge the generalizability of consequently preliminary findings.
To explore individual conceptualisations of ON within specific contexts, the second research project combined a text-mining approach with a qualitative analysis to investigate comments posted on one of the most popular online discussion forums, Reddit. Two-hundred-forty-six comments that discussed ON were extracted from a publicly available data archive, and subsequently analysed using thematic analysis. As ON had been associated with both EDs as well as specific (restricted) diets and lifestyles, this study compared two different topical environments: ED-related versus diet-related subreddits. In both subreddit communities ON was linked to ED behaviours, food safety concerns, and moral superiority. Discrepancies between subreddit categories mostly involved ON’s conceptualisation as a (distinct) disorder. Shifting expressions of EDs as well as perceptions of problematic dietary norms were identified as complicating a clear definition of ON.
Based on these findings, a third study was carried out to further investigate the perceived overlap between ON and ED symptoms from a clinical practice perspective. Interviews with ten mental health professionals working in the field of EDs were conducted to explore their professional experiences with the prevalence, development, and maintenance of excessive healthy eating motivations in ED populations. Overall, findings from this study suggest that sociocultural developments influence the expression of all ED presentations, with current health and wellness ideals further blurring the lines between conceptualisations of ON and other EDs. It was therefore concluded that ON-related ED presentations need to be contextualised within the framework of current societal messages around health, while ON’s unique characteristics as a disorder require further investigation.
With all preceding studies highlighting difficulties regarding a clear conceptualisation of ON, especially in relation to its differentiation from other EDs, the final study aimed to explore how general health-promoting behaviours relate to disordered eating across time. A one-year longitudinal study was conducted to measure changes in disordered eating and health-related coping behaviours during the COVID-19 pandemic, a time of heightened health (risk) awareness. Both people with and without an ED were recruited. Using latent growth curve analysis, the relationship between disordered eating and health-related coping was investigated. Interestingly, individual levels of disordered eating and health-related coping were positively related at all measured timepoints. A past or present ED diagnosis significantly predicted higher levels of both disordered eating and health-related coping. While disordered eating levels slightly decreased throughout the specified timeframe, health-related coping behaviours displayed near stable values. This final study provided further evidence for the positive association between disordered eating and health-related behaviours. Especially during stressful experiences, specific health behaviours might constitute a means to control negative emotional states or to feel a sense of mastery, as has been reported for other ED behaviours. However, potential mechanisms underlying this relationship require further investigation.
Across the four studies, health motivations and behaviours have been shown to be relevant for current ED manifestations. Based on the findings illustrated in the present thesis, ON is currently associated with a variety of clinical presentations, lifestyle habits, and societal demands, which complicates the progression of research in this field. Key findings of this thesis relate to the need for more culturally embedded research around ON and more differentiated public health policy work, integrating health promotion strategies and campaigns with ED-related policy work. Future research will need to utilize longitudinal and interdisciplinary approaches to further explore the unique developmental pathways of an ON symptomatology and related excessive health concerns. The clinical utility of an ON diagnosis will need to be explored by investigating its distinct aetiology and progression, as well as the need for unique treatment approaches and barriers to accessing support.||en