Researchers in the U. S. have found that people with anorexia nervosa have strikingly high levels of fat within their bone marrow.

According to the researchers at Children's Hospital Boston, their findings are based on MRI imaging of the knees of 20 girls with anorexia and 20 healthy girls of the same age.

"It's counter-intuitive that an emaciated young woman with almost no subcutaneous fat would be storing fat in her marrow," Dr. Catherine Gordon, the senior investigator and director of the

bone health program at Children's Hospital Boston, said in a statement.

During the study, the knee magnetic resonance imaging images were read by radiologists who were unaware of the patient's clinical status. The patients with anorexia had markedly increased fat

content - visualized as "yellow marrow" - as compared to controls. They also had less than half as much healthy red marrow in the lower thigh bone and upper shinbone.

Dr. Gordon further said, "Bone formation is very low in girls with anorexia, and that's a particular problem because they are growing adolescents who should be maximally forming bones. But

because of the hormonal alterations induced by malnutrition, the bone marrow stops yielding the needed cells to form bone. Instead the stem cells are pushed toward fat formation."

Journal of Bone and Mineral Research have published the findings of the study.