The causes of anorexia nervosa are complex and may vary from person to person. The main cause is psychological rather than physical and may be linked to fear of being teased about being overweight, stress, insecurity or a need to rebel against figures of authority.

Girls in their teens are most at risk of anorexia nervosa - it is quite rare before puberty. About ten times as many girls as boys suffer from the condition. Girls who are under a lot of stress to perform - either academically or at sport - are especially at risk.

Anorexia nervosa often starts gradually with a 'normal' slimming diet. Gradually you may begin getting worried about eating too much and start counting the calories in everything. You may want to weigh yourself very often and how you feel will depend on how much weight you have lost. You may become anxious about eating with other people and make excuses to avoid doing so. You may feel that all or part of you is still very fat and become irritated when people comment about your weight.

You may feel the need to exercise a lot and vomit or take laxatives to prevent you from absorbing food. You may become very interested in cooking and in making sure other members of the family eat well. When you have anorexia nervosa your periods will stop, your hair and skin will be dull and lifeless and you may get a fine downy hair over your body. You will feel very tired and cold and may notice that your hair fails out or wounds do not heal properly. You may also feel depressed and anxious.

If you are worried that you may be suffering from anorexia nervosa make an appointment to talk to your GP. He or she will be able to give you general advice about the condition and help you to understand what help if any you need.

This depends on how bad the condition is. If it is not too advanced the main treatment will revolve around getting you to accept that there is a problem and taking steps to tackle it. Such treatment centres on moving gradually towards eating more food more regularly and setting goals for maintaining or gaining weight.

Anorexia nervosa can cause severe physical complications and sometimes you may need to be referred to a specialist team or admitted to hospital for treatment, including psychiatric counselling and controlled feeding.

Anorexia nervosa is a long-term condition and it is likely that you will need long-term counselling and follow-up. It is possible you will become anxious about your eating again when you are under particular stress. If you do, it is important to seek help early to stop matters getting worse.