Anorexia nervosa is a very serious eating disorder. It may lead to death as a consequence of starvation or other medical conditions caused by lack of food. The limit for anorexia is usually put at a BMI of less than 17.5 in combination with other symptoms. Between a half and one percent of young people suffer from anorexia.

Those who eat too little as a consequence of a disease are not classified as having anorexia nervosa.

Those who either won't or can't eat sufficient food are classified as having anorexia nervosa.

The desire to avoid eating too much is often combined with an excessive fear of becoming fat and extreme notions about wholesome and unwholesome food.

It can also depend on an addictive condition where starvation stimulates the body's reward centre.
Those with anorexia frequently deny that they are underweight, or ill, just as alcoholics deny that they are addicted to alcohol.

Women with anorexia often miss their menstruation several times in succession.

There are two main types of personality who are subject to anorexia:
The restrictive type who limits all their eating and often have a strong will.
The compulsive eating type who alternate between eating and removing all excessive nutrition in the same way as those with bulimia . Those with this type of problem often have other addictive conditions and difficulties with impulse control.
There are various contributory causes of eating disorders and often several of these may act in combination.
The ability to distinguish between hunger, satisfaction and other feelings is learned when one is very young. More . Faulty upbringing can interfere with this. The effect is often not noticed until later in life. More .
Eating disorders often arise when a person tries to reduce to an abnormally low weight. The unnatural slim ideal may be therefore a contributory cause of eating disorders.
Many people with eating disorders are not aware of their physical feelings of hunger and satisfaction. Thus, they lack a natural control of their eating. Such people will easier be pulled into eating disorders, where they use eating to conceal feelings and escape from constructive problem solutions. More .
Both overeating and fasting can stimulate the reward centre in the brain. Eating disorders therefore function in the same way as alcoholism and drug addiction. The same personality traits which increase the risk of alcoholism and drug addiction also increase the risk of eating disorders. More.
The personality traits which increase the risk of eating disorders are partly hereditary. Addictive problems or affective disorders (depression, etc.) are more common among relatives.
Some of the personality traits involved are: a tendency to please others and a low ability to assert one's own needs; a need to reduce unsettling feelings of anxiety, depression and low self-confidence; perfectionism and problems with impulse control.

Eating disorders are more common among women and those who are affected by social attitudes and body ideals and who also lack the ability of following their own feelings and needs. More .
Children of overweight parents, and parents with an exaggerated interest in body shape, more often get eating disorders. Also, demands from the family and insecure family circumstances increase the risk.
Overweight occurs if you eat more fat than your body can consume. Both biological (somatic) and life-style factors can cause overweight. Eating disorders (see above) can also cause overweight. More . There are also some illnesses and drugs which can make a person more susceptible to overweight.
It takes time to get well and you must work on yourself.

Suppose you have inherited an old house full of rubbish and in need of repair. It takes a lot of purposeful work to make it a beautiful, functional home, but it can be done if you work hard. It is, maybe, not so important which room in the building you start with, but it is important to start somewhere, otherwise nothing will happen. Important problems to attack if you have an eating disorder:

Switch to a diet containing wholesome food which does not lure you into overeating. More
The food should also be based on ingredients with a low glycemic index. More
Learn to recognize your feelings of physical hunger and satisfaction. Eat only in response to physical hunger and stop when you are satisfied. More
Learn to recognize true feelings and solve problems. Don't flee from unpleasant feelings by means of starvation, vomiting or compulsive eating. Accept and allow yourself to feel unpleasant feelings.
Consider the whole of your life: studies, work, friends, spare time, family, home, etc. Where can you make improvements?
Try to think in a constructive way so that you don't make unnecessary difficulties for yourself.

Is Anorexia Nervosa a psychosis?
Some experienced therapists say that anorexia is a psychotic disorder since the individual doesn't have any awareness of illness. Another view is to see anorexia as an addictive condition, and here the addict also often has no awareness of illness. Hunger reduces mental suffering. If the intake of calories is less than 400 kcal a day, the sensation of hunger disappears, the person becomes calm and gets a feeling of control.

There are two types of anorexia:
One type is like bulimia, although the excessive eating is followed by starvation or vomiting, and the final result is to weigh too little.
The other type continually eats far too little.

Self-starvation reduces the amount of the hormone serotonin which can be experienced as anxiety and distress. The type of anorectics who continually eat too little are often individuals whose levels of serotonin are too high, and consequently they experience anxiety and distress. Starvation reduces the high levels of serotonin and makes their raging emotions calmer.

The type of anorexia which is really a variation of bulimia is (as well as bulimia) is caused by insufficient levels of serotonin. The excessive eating combats the depression which may follow the production of insufficient serotonin.