Bodies from the inside out: an investigation of the relationships between interoception and body image

Interoception refers to the processing of internal bodily stimuli, while body image refers to appearance-related perceptions, affect, and cognitions. Previous research has identified an inverse relationship between interoception and body image, with people who have lower levels of self-reported and behavioural interoceptive ability tending to report more negative body image. In the present thesis, I sought to examine whether this association is upheld across multiple components of interoception and body image, and after accounting for key demographic variables. Studies 1-4 investigated associations between facets of self-reported interoceptive awareness and body image in online samples of adults (N = 646) and adolescents (N = 265) from the United Kingdom (UK) and a sample of Malaysian adults (N = 815). Study 5 investigated associations between facets of body image and a behavioural measure of gastric interoception (i.e., a two-stage water load task) in samples of UK (n = 91) and Malaysian (n = 100) adults. Study 6 investigated associations between facets of body image and implicit measures of cardiac and gastric interoception (i.e., heartbeat evoked potential and gastric-alpha phase-amplitude coupling) in UK adults (N = 35). Significant associations between interoception and body image were identified in all six studies, across dimensions of body image and hierarchical levels of interoceptive processing, in several demographically distinct samples. However, the pattern of the associations was found to be dependent on the components of interoception and body image being examined: broadly, greater self-reported interoceptive awareness is associated with a more positive body image, and lower implicit and behavioural interoceptive sensitivity is associated with more negative body image. While many of the findings aligned with existing theoretical accounts of the association between interoception and body image, several of the findings also indicate that it is necessary to refine extant theoretical accounts to encompass the multidimensionality of interoception and body image.