Anorexic people appear to be less able to judge the size of their own bodies than that of others. This was the finding of an intriguing new French study published this week in the open access journal PLoS ONE.

People with anorexia usually report feeling their bodies are bigger than they actually are. But this is not easy to investigate in research.

Dewi Guardia of the University Hospital of Lille in France, and colleagues, have been studying how patients with anorexia nervosa perceive whether their bodies can fit through different sizes of door openings. In a previous study they found anorexic patients perceived they would not pass through the doorways, even though in reality they were easily wide enough.

In this new study, they invited 25 patients with anorexia and 25 healthy controls to look at a door-like opening and judge whether it was wide enough for themselves to pass through, and also to judge whether it was wide enough for another person present in the testing room to pass through.

The results showed that the anorexic patients were much better at judging whether the other person would fit through the door than whether their bodies would fit through it.

The researchers also found a strong link between anorexics’ perception of own ability to pass through the door and their body weight before they became anorexic suggesting they still saw themselves as being their previous size.

“Our results suggest that body overestimation can affect judgments about the capacity for action but only when they concern the patient’s own body. This could be related to impairments of the overall network involved in the emergence of the body schema and in one’s own perspective judgments,” conclude the authors.

In their discussion, they note that anorexia nervosa mainly affects young women aged between 15 and 19, a period where young bodies undergo many neurological, morphological and psychological changes.

“Weight changes induced by eating disorders could enhance these disturbances,” they suggest.

They also reflect on whether the inability of anorexics to accurately assess their own body size has parallels in amputees continuing to feel the presence of a phantom limb after amputation. Is there a similar lack of updating in the various systems that integrate sensory perception with self-perception?

A mismatch between the actual sensory feedback and the cortical regions representing the body may lead to the maintenance of an incorrect body representation. Future research and therapeutic approaches (especially virtual reality, for example) could focus on these targets,” they urge.

The researchers also point out that their study was with a small group of participants, so their findings are tentative, and would need to be confirmed with a larger sample.

Written by Catharine Paddock PhD