I have been advocating for a long time that most mood disorders are a sign of nutritional disorders or which anorexia and bulimia are specific cases. Much of this is closely related to insulin resistance, leading to hypoglycemic conditions. In insulin resistance - especially pre-diabetic insulin resistance - the body has problems converting carbohydrates into Biological Energy called (ATP).
This biological energy is essential for the body to convert one set of molecules to another set of molecules - such as in the conversion of tryptophan (found in food) into serotonin - a feel good neurotransmitters in the brain. Without that energy we are going to feel depressed whilst at the same time triggering a low self-esteem. Because sugars are not converted to energy it accumulates in the body as fat cells. Thus the classical condition of anorexia is that a person - usually young women - finds that they are putting on weight and feeling depressed start to "DIET" in the hope of losing weight. This is the very mechanism to aggravate the mood disorder and will prompt the person to make greater efforts "to lose weight".
Another important factor of anorexia is an undiagnosed Hypothyroidism responsible for low blood sugar levels (and energy sources), which can also cause undesirable weight gains. Whatever the cause(s) the results is that the person on a starvation diet, deprives the body of essential nutrients and co-enzymes to maintain health and mental health. One of the co-enzymes usually found missing in anorectic/bulimic patients is zinc, the deficiency of which causes loss of taste and smell without which the person will lose appetite and the normal enjoyment of food intake. Thus we see a self-fulfilling prophecy. Many other missing nutrients contribute to severe mental illness and cognitive abnormalities.
The tragedy of this disease is that the person firmly believes that her misery is caused by a faulty mind and that somehow by re-thinking one's attitudes and believes or re-exploring one's' childhood experiences, with the help of talk-therapy one can overcome anorexia and/or bulimia. Amazingly enough this delusion is often reinforced by psychotherapists who share this delusion with their clients.
It is important to realize that the nutritional-biochemical aspects of the disease must be treated FIRST before considering repairing any psychological damage caused by the disease.
See:
Eating Disorders
Treatments for Anorexia and Eating Disorders
Please consult a Nutritional Doctor, Clinical Nutritionist or a Nutritional Psychologist if self-help therapy fails.