Anorexia nervosa is an eating disorder affecting mainly girls or women, although boys or men can also suffer from it. It usually starts in the teenage years.

It is difficult to estimate how common it is but surveys suggest that up to 1 per cent of schoolgirls and female university students have anorexia nervosa. This may be an underestimate.

• Weight loss of at least 15 per cent below the normal ideal body weight for a person of the same age and height.
• Cessation of periods or delayed development in puberty.
• Self-induced weight loss. Methods can include fasting, low food intake, excessive exercise, diuretic medicines (medicines that make you urinate more) laxatives, diet pills or vomiting. Sometimes people make themselves sick to lose weight. Others take excessive exercise.
• Sufferers have a constant fear of gaining weight, as well as a feeling of being fat, even when their weight is much less than that of other people of the same height.
• Sufferers may feel bloated, even after a small meal.
• They may lose interest in socialising with friends.
• Other side effects include tiredness, feeling cold, constipation and stomachache.
• Some patients also develop additional disorders such as bulimia.