A person developing anorexia nervosa exhibits important warning signs. At first, dieting becomes the life focus. The person may think, "The only thing I am good at is dieting. I can't do anything else." This innocent beginning often leads to very abnormal self-perceptions and eating habits, such as cutting a pea in half before eating it. Other habits include hiding and storing food and or spreading food around a plate to make it look as if much has been eaten. An anorexic person may cook a large meal and watch others eat it while refusing to eat anything. Anorexics may also exercise compulsively to the point that it is obsessive and driven. It can interfere with life activities or occur at inappropriate times or settings—for example, doing squats while brushing teeth.
As the disorder progresses, the range of foods may narrow and be rigidly divided into safe and unsafe ones, with the list of safe foods becoming progressively shorter. For people developing anorexia nervosa, these practices say, "I am in control." These people may be hungry, but they deny it, driven by the belief that good things will happen by just becoming thin enough. It becomes a question of willpower.
Soon people with anorexia become irritable and hostile and begin to withdraw from family and friends. School performance generally crumbles. They refuse to eat out with family and friends, thinking, "I won't be able to have the foods I want to eat," or "I won't be able to throw up afterward."
Anorexic persons see themselves as rational and others as irrational. They also tend to be excessively critical of themselves and others. Nothing is good enough. Because it cannot be perfect, life appears meaningless and hopeless. A sense of joylessness colors everything.
As stress increases in the person's life, sleep disturbances and depression are common. Many of the psychological and physical problems associated with anorexia nervosa arise from insufficient energy intake, as well as deficiencies of nutrients, such as thiamin and vitamin B-6. For the latter reason, a multivitamin and mineral supplement is typically prescribed in therapy. For a female, the combination of problems— coupled with lower and lower body weight and fat stores—causes menstrual periods to cease. This may be the first sign of the disease that a parent notices and represents the hallmark of the disease.
Ultimately, an anorexic person eats very little food; 300 to 600 kcal daily is not unusual. In place of food, the person may consume up to 20 cans of diet soft drinks and chew many pieces of sugarless gum each day.