Zusammenfassung
Aims: Anorexia nervosa (AN) is a serious eating disorder that goes along with underweight and high rates of psychological and physical comorbidity. Body image disturbance is a core symptom AN, but as yet distinctive features of this disturbance are unknown. This study uses individual 3D-avatars in virtual reality to investigate the following questions: (1) Do women with AN differ from controls in how accurately they perceive their body weight and (2) in what body weight they desire?
Method: We investigated n=24 women with AN (body mass index (kg/m2, BMI) M=15.17, SD=1.47) and n=24 healthy controls (BMI M=22.07, SD=1.85). Based on a 3D body scan, we created individual avatars for each participant. Each avatar was manipulated to represent +/5, 10, 15 and 20 of the participant’s weight. Avatars were presented on a stereoscopic life-size screen. Using an 1 Alternative Forced Choice (1AFC) task and a Method of Adjustment (MoA) task, participants were asked to identify/adjust their correct body weight and their desired weight. Additionally, eating pathology, body dissatisfaction and self-esteem were assessed. In a control experiment, we repeated all tasks with an avatar that had the participant’s body shape, but another person’s look.
Results: Women with AN and controls underestimated their current weight, with a trend that women with AN underestimated even more than controls (1AFC: AN M=-7.38, SD=4.71; Con M=-3.80, SD=5.02; F(1,45)=6.35, p<.05; MoA: AN M=-5.94, SD=5.81; Con M=-3.19, SD=4.89, F(1,45)=3.09, p=.086). The discrepancy between desired and actual body weight suggested that both groups wanted to lose weight, and in percent of own body weight, controls even more so (AN M=-2.11, SD=8.12; Con M=-9.08, SD=6.13, F(1,45)=11.10, p<.01). Of note, the average desired body of the control group still had normal weight while the average desired body of women with AN had a BMI of 14.67, which would correspond to extreme AN. Correlation analyses revealed that desired body size, but not accuracy of body size estimation, was associated with eating disorder symptoms. The control experiment generally yielded the same result pattern.
Conclusions: Our results contradict the widespread assumption that patients with AN overestimate their body size. Rather, they illustrate how fundamentally they prefer extremely thin bodies. According to our observations, clinical interventions should aim at helping patients with AN to change their desired weight.
