Making the Diagnosis
To diagnose eating disorders, doctors generally only need signs and symptoms based on a physical exam and a detailed medical or personal history. In the case of a person with anorexia, continued weight loss at a low or normal weight, obsessive exercise, progressive food restriction, depression, and falling grades at school or poor work productivity should raise suspicion.
The medical diagnosis of anorexia nervosa is made when the person's weight has dropped to at least 15% below the minimum normal weight for their age and height due to a pathological fear of obesity. Blood tests reveal abnormalities in hormone levels that help confirm the diagnosis for both anorexia and bulimia. However, there is no test that is diagnostic and the diagnosis of anorexia is made by clinical assessment.