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.
Anticholinergics (anticholinergic agents) are substances that block the action of the neurotransmitter called acetylcholine (ACh) at synapses in the central and peripheral nervous system.These agents inhibit the parasympathetic nervous system by selectively blocking the binding of ACh to its receptor in nerve cells. The nerve fibers of the parasympathetic system are responsible for the involuntary movement of smooth muscles present in the gastrointestinal tract, urinary tract, lungs, sweat glands, and many other parts of the body.In broad terms, anticholinergics are divided into two categories in accordance with their specific targets in the central and peripheral nervous system and at the neuromuscular junction: antimuscarinic agents, and antinicotinic agents (ganglionic blockers, neuromuscular blockers).The term "anticholinergic" is typically used to refer to antimuscarinics which competitively inhibit the binding of ACh to muscarinic acetylcholine receptors; such agents do not antagonize the binding at nicotinic acetylcholine receptors at the neuromuscular junction, although the term is sometimes used to refer to agents which do so.