Restricting type: the individual uses restricting food intake, fasting, diet pills, or exercise as a means for losing weight; they may exercise excessively to keep off weight or prevent weight gain, and some individuals eat only enough to stay alive. In the restrictive type, there are no recurrent episodes of binge-eating or purging present. Levels of severity
Body mass index (BMI) is used by the DSM-5 as an indicator of the level of severity of anorexia nervosa. The DSM-5 states these as follows:
Mild: BMI of greater than 17
Moderate: BMI of 16–16.99
Severe: BMI of 15–15.99
Extreme: BMI of less than 15

Investigations
Medical tests to check for signs of physical deterioration in anorexia nervosa may be performed by a general physician or psychiatrist, including:

Complete blood count (CBC): a test of the white blood cells, red blood cells and platelets used to assess the presence of various disorders such as leukocytosis, leukopenia, thrombocytosis and anemia which may result from malnutrition. Urinalysis: a variety of tests performed on the urine used in the diagnosis of medical disorders, to test for substance abuse, and as an indicator of overall health
Chem-20: Chem-20 also known as SMA-20 a group of twenty separate chemical tests performed on blood serum. Tests include protein and electrolytes such as potassium, chlorine and sodium and tests specific to liver and kidney function. Glucose tolerance test: Oral glucose tolerance test (OGTT) used to assess the bodys ability to metabolize glucose. Can be useful in detecting various disorders such as diabetes, an insulinoma, Cushings Syndrome, hypoglycemia and polycystic ovary syndrome.
One of the most known psychotherapy in the field is CBT-E, an enhanced cognitive-behavior therapy specifically focus to eating disorder psychopathology. Acceptance and commitment therapy is a third-wave cognitive-behavioral therapy which has shown promise in the treatment of AN. Cognitive remediation therapy (CRT) is also used in treating anorexia nervosa. Schema-Focused Therapy (a form of CBT) was developed by Dr. Jeffrey Young and is effective in helping patients identify origins and triggers for disordered eating. Diet
Diet is the most essential factor to work on in people with anorexia nervosa, and must be tailored to each persons needs. Food variety is important when establishing meal plans as well as foods that are higher in energy density. People must consume adequate calories, starting slowly, and increasing at a measured pace. Evidence of a role for zinc supplementation during refeeding is unclear. Medication
Pharmaceuticals have limited benefit for anorexia itself. There is a lack of good information from which to make recommendations concerning the effectiveness of antidepressants in treating anorexia. Administration of olanzapine has been shown to result in a modest but statistically significant increase in body weight of anorexia nervosa patients. Admission to hospital
Patients with AN may be deemed to have a lack of insight regarding the necessity of treatment, and thus may be involuntarily treated without their consent. : 1038  AN has a high mortality and patients admitted in a severely ill state to medical units are at particularly high risk.