Body image disturbance (BID) is a core symptom of anorexia nervosa (AN), but as yet distinctive features of BID are unknown. The present study aimed at disentangling perceptual and attitudinal components of BID in AN.

We investigated n = 24 women with AN and n = 24 controls. Based on a three-dimensional (3D) body scan, we created realistic virtual 3D bodies (avatars) for each participant that were varied through a range of ±20% of the participants’ weights. Avatars were presented in a virtual reality mirror scenario. Using different psychophysical tasks, participants identified and adjusted their actual and their desired body weight. To test for general perceptual biases in estimating body weight, a second experiment investigated perception of weight and shape matched avatars with another identity.

Women with AN and controls underestimated their weight, with a trend that women with AN underestimated more. The average desired body of controls had normal weight while the average desired weight of women with AN corresponded to extreme AN (DSM-5). Correlation analyses revealed that desired body weight, but not accuracy of weight estimation, was associated with eating disorder symptoms. In the second experiment, both groups estimated accurately while the most attractive body was similar to Experiment 1.

Our results contradict the widespread assumption that patients with AN overestimate their body weight due to visual distortions. Rather, they illustrate that BID might be driven by distorted attitudes with regard to the desired body. Clinical interventions should aim at helping patients with AN to change their desired weight.

Previous neuroimaging studies have demonstrated abnormalities in visual body image processing in anorexia and bulimia nervosa, possibly underlying body image disturbance in these disorders. Although cognitive behavioural interventions have been shown to be successful in improving body image disturbance in eating disorders, no randomized controlled study has yet analysed treatment-induced changes in neuronal correlates of visual body image processing.

Altogether, 32 females with eating disorders were randomly assigned either to a manualized cognitive behavioural body image therapy consisting of 10 group sessions, or to a waiting list control condition. Using functional magnetic resonance imaging, brain responses to viewing photographs of one's own and another female's body taken from 16 standardized perspectives while participants were wearing a uniform bikini were acquired before and after the intervention and the waiting time, respectively.

Data indicate a general blood oxygen level dependent signal enhancement in response to looking at photographs of one's own body from pre- to post-treatment, whereas exclusively in the control group activation decreases from pre- to post-waiting time were observed. Focused activation increases from pre- to post-treatment were found in the left middle temporal gyrus covering the coordinates of the extrastriate body area and in bilateral frontal structures including the middle frontal gyrus.

Results point to a more intense neuronal processing of one's own body after the cognitive behavioural body image therapy in cortical regions that are responsible for the visual processing of the human body and for self-awareness.