title: Investigating the Similarities and Differences Between Orthorexia Nervosa and Eating Disorders Using Implicit and Explicit Measures
Creators: name: Clifford, Rosemary
Publisher: name: The Australian National University
Year: 2025

description: The term Orthorexia Nervosa (ON) emerged in the 1990s to describe a condition characterised by an obsessive preoccupation with healthy/pure eating that leads to physical and psychological impairment. Since its inception, there have been several debates regarding ON, including questions about where it is best categorised in diagnostic manuals, whether it represents a new eating disorder (ED) or a subtype of a currently recognised ED, and whether body image concerns are a feature. The current research aimed to inform such debates through three studies comparing participants with elevated ON symptoms and ED symptoms (ED/ON), participants with elevated ED symptoms (ED), and healthy comparison (HC) participants (i.e., an absence of ON or ED symptoms and no history of shape/weight concerns). Study 1 investigated the presence of ED symptomatology, body image concerns (appearance focus and appearance satisfaction), psychological distress, ED-specific impairment, and general mental and physical health in those with elevated ON symptoms compared to those without. Results indicated that higher levels of ED symptomatology, appearance focus, and ED-specific impairment were found among those in the ED/ON group relative to the ED and HC groups. The ED/ON group was comparable to the ED group, but higher than the HC group, in terms of appearance satisfaction, psychological distress, and general mental and physical health. Study 2 investigated the implicit associations to food and body stimuli of those with ON compared to those without. This study compared the implicit associations of the same three groups of participants as Study 1 utilising three Implicit Association Tests (IAT) assessing attitudes towards health- versus appearance-based stimuli. These included two picture-based IATs (one assessing attitudes towards healthy/average-weight female bodies versus thin/unhealthy female bodies, and one assessing attitudes towards healthy/high-calorie foods versus low-calorie/unhealthy foods) and one questionnaire-based IAT (assessing attitudes towards health- versus appearance-focused statements). Results indicated that participants across all groups exhibited a more favourable view towards the health-based stimuli than the appearance-based stimuli, with the ED/ON participants exhibiting the least favourable view towards the health-based stimuli among the three groups, and the ED and HC participants exhibiting comparable attitudes. Finally, Study 3 investigated the cognitive processing of those with ON compared to those without by focusing on attentional bias towards food and body stimuli. Utilising the same participant sample and stimuli image sets as Study 2, attentional biases towards healthy/average-weight bodies, thin/unhealthy bodies, healthy/high-calorie food, and low-calorie/unhealthy food images were assessed using a series of Visual Probe Detection Tasks (VPDTs). Results indicated that the ED/ON group demonstrated greater attentional bias towards thin/unhealthy bodies, healthy/high-calorie, and unhealthy/low-calorie food compared to the ED and HC groups, but not for healthy/average-weight bodies. Overall, the current research indicated that ON symptoms in the context of an ED were associated with a greater focus on appearance and more elevated levels of ED-specific impairment, a less favourable view of health-based stimuli, and a greater attentional bias to food and body stimuli. If replicated, the findings suggest that the additional presence of ON symptoms in those with an ED signifies a more severe presentation, which has both diagnostic and treatment implications.