According to a leading expert, severe cases of anorexia may be the result of undetected autism in women.
Professor Christopher Gillberg, of the University of Strathclyde, says that autism, characterised by defects in communication and social interaction, also makes many anorexic patients unresponsive to traditional treatments and may be responsible for anorexia's low recovery rates.
Professor Gillberg believes that although autism is thought to be predominately a male problem, affecting up to four times more boys than girls, the disorder has been overlooked in women because their autistic traits present themselves differently.
For example an obsession with counting calories may be an outward sign of autism.
He says their research has shown that a small but important minority of all teenage girls, with anorexia nervosa in the general population, meet the diagnostic criteria for autistic disorder, Asperger syndrome or atypical autism.
He has apparently seen quite a number of cases where the anorexia has become completely entrenched because people have not understood that underlying the eating disorder is autism.
Professor Gillberg says anorexic patients with autism tend to be severe cases because traditional treatment for eating disorders proved ineffective.
A good example is family therapy, a popular psychotherapy in which family members discuss eating with the sufferer which is all but useless for autistic patients.
People with an autism spectrum disorder have great difficulty even understanding basic concepts about other people's thoughts and feelings, which means that anything said in a family-therapy session is likely to be misconstrued by the affected individual who will not grasp what is going on in that particular context.
They need far more concrete, one-to-one interventions.
A spokesman for the Eating Disorder Association welcomed the research and said it could help develop more effective treatments for eating disorders.
About 5 per cent of anorexic patients die from complications of the disorder and only 40 per cent make a full recovery.
Ten per cent of the 1.1 million reported anorexia cases in the UK are in men, and Professor Gillberg says autism is behind the majority of male anorexia cases.
He says his clinical impression over the past 30 years has been that males struck by anorexia nervosa very often have autism spectrum disorders.
Judith Gould, director of the National Autistic Society's Diagnostic Centre, agrees with the study's findings, and feels autism in girls is being missed because it often manifests itself in females in different ways.
She agrees that anorexia, which is predominantly diagnosed in girls, could be linked to autism in an unknown proportion of cases.
About 500,000 people in the UK are thought to have some form of autism.