Characterising the psychophysiological experience of being underweight or obese: Preliminary Evidence from a Virtual Reality Study

Body-related self-disgust (BRSD), a profound sense of aversion toward one's own body, has been identified as a potent emotional stressor, especially in individuals with eating disorders (EDs). This study aims to characterise BRSD at psychological and physiological (cardiac and gastric) levels. Participants were exposed, in counterbalanced order, to two virtual reality scenarios. In one session, BRSD was elicited through the embodiment of avatars with different body sizes (underweight, normal-weight, and obese). In the control session, participants watched, in a virtual cinema, disgusting versus neutral video clips, unrelated to their own body. Disgust was assessed via self-reports, electrocardiogram, and electrogastrography. Thirty-nine normal-weight healthy females (mean age = 21.9 years; mean BMI = 21.5) participated in the study. Preliminary findings suggest that underweight (BMI 17) and obese (BMI 40) avatars were embodied less and perceived more negatively (greater sadness, guilt, discomfort) compared to the normal-weight avatar (BMI 21). BRSD was most pronounced during the embodiment of the obese avatar. Physiological data show increased heart rate variability (HRV) when watching disgusting videos, with a similar trend during embodiment of the obese avatar. Correlational analyses reveal that gastric sensations were positively associated with BRSD during embodiment of both the underweight and obese avatars. Additionally, BRSD triggered by the underweight avatar correlated with cardiac sensations and HRV. Although preliminary, these findings suggest that embodying an obese or underweight body triggers BRSD and gastric sensations, accompanied by autonomic changes. Characterising the psychophysiological correlates of BRSD may provide insight into its mechanisms and support its role as a potential transdiagnostic marker of ED psychopathology, informing novel targeted intervention development.