I'm in a virtual body: a locked allocentric memory may impair the experience of the body in both obesity and anorexia nervosa

In a recent paper Guardia and colleagues (1) observed an altered representation of the body in an obese patient: the patient experienced both implicitly and explicitly a wider body even after a successful weight reduction (before: 125Kg; after: 60 Kg). On one side, this outcome is not uncommon and has been found also in about 30% of the patients experiencing laparoscopic adjustable gastric banding (2). On the other side, this result has some similarities with another recent work by Guardia and colleagues with anorexia nervosa patients (3): the patients experienced both implicitly and explicitly a wider body and the magnitude of the overestimation was correlated with the size of the patient's body prior to disease onset. These data suggests a possible role of an impaired memory of the body in the aetiology of body image distortion in both obesity and anorexia nervosa. Specifically, according to the Allocentric Lock Hypothesis (4, 5) individuals with these disorders may be locked to an allocentric (from outside) memory of the body that is no longer updated by contrasting egocentric representations driven by perception. The main effects of this cognitive bias are two: experiential and cognitive. The first is the permanent experience of a "wrong" body, totally independent by the shape or the size of the real body: whatever the subjects will do to modify their real body, they will always be present in a virtual body (the allocentric memory) that is different from the real one. The second effect is cognitive: the allocentric memory reorganizes existing memories and structure the acquisition of new ones. Specifically, the virtual body stored in the memory produces a priming effect on any body related experience drawing the subjects' attention to previously stored body related stimuli and biasing interpretation of future body-relevant events. A possible key to unlock this virtual body is virtual reality: a recent controlled trial (6) with obese BED and a case study with an obese bariatric patient (7) demonstrated the ability of a virtual reality enhanced cognitive behavioural approach in reducing body image dissatisfaction and in improving the long term outcome of the treatment.