Anorexia nervosa (AN) and bulimia nervosa are two common eating disorders.
AN is characterized by food restriction and irrational fear of gaining weight, as well as a distorted body self-image. Those suffering from AN often view themselves as “too fat” even if they are often emaciated. Recent studies show the onset age has recently decreased from an average of 15 years of age to 10 years of age. It occurs in ten times more females than males. The average caloric intake in AN is 500–800 calories per day, but extreme cases of complete self-starvation require intravenous feeding.
AN is a serious mental illness with a high incidence of comorbidity (especially autism and depression) and mortality similar to other serious psychiatric disorders. People suffering from AN have extremely high levels of ghrelin (the hunger hormone that signals a physiological desire for food) in their blood. The high levels of ghrelin suggest that their bodies are desperately trying to make them hungry; however, that hunger call is being ignored or suppressed.