The more prominent this fault was the fatter anorexics fal
When anorexics look in the mirror many are convinced their bodies are larger than they are.
This spurs them to try and keep their weight as low as possible by restricting their diet or exercising excessively.
Now scientists have discovered this misjudgment is due to a 'connection error' in the brain.
Body image: Scientists studies key areas in the left hemisphere in the brain which processes how we view ourselves
Researchers at Ruhr University Bochum in Germany studied the network of brain regions that become active when people see pictures of bodies.
They asked ten anorexic and fifteen healthy women of a similar age to judge on a computer which of several different silhouettes corresponded best to their own body shape. Ten control subjects who did not participate in the MRI scan answered the same question by matching a photo of the test subject to the right silhouette.
Scientist found that while healthy subjects rated themselves as thinner than the control subjects, those with the eating disorder perceived themselves to be fatter than the control subjects did.
The team then recorded the brain activity of the 25 participants using MRI scanners, while they observed photos of bodies.
They analysed the activity in the 'fusiform body area' (FBA) and the 'extrastriate body area' (EBA) in the left hemisphere of the brain.
When people look at body images, the visual information first enters in the central occipital lobe (mOC). The 'fusiform body area' (FBA) and the 'extrastriate body area' (EBA) then process the images further. In anorexic women, the connection between the FBA and EBA is weaker than in healthy women
Previous studies have shown that these brain regions are critical for how people process images of bodies.
They found the connection between the two regions, which process body images was weaker among anorexic women than in healthy women.
The more prominent this 'connection error' was, the more overweight the respondents considered themselves to be.
'These alterations in the brain could explain why women with anorexia perceive themselves as fatter, even though they are objectively underweight,' said study author Professor Dr Boris Suchan.
He added: 'In a previous study we found that there are structural changes in the brains of patients with anorexia. They have a lower density of nerve cells in the EBA. '
The latest study found the EBA received reduced input from the FBA.
'These changes could provide a mechanism for the development of anorexia,' said Dr Suchan.
The study was published in the journal Behavioural Brain Research.
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