Anorexia nervosa is an eating disorder that mainly affects girls or women, although boys or men can also suffer from it. It usually starts in the teenage years. It is difficult to estimate the prevalence of the disease but surveys in the US suggest that up to one per cent of schoolgirls and female university students have anorexia nervosa. In India, most cases go undiagnosed.

• Body weight is maintained at least 15 per cent below that expected for a person's height
• It is self-induced weight loss by avoiding fattening foods and may involve excessive exercise, using laxatives or diuretics or self-induced vomiting
• There is a strong, almost overwhelming fear of putting on weight, with sufferers preoccupied with the shape or size of their bodies
• Rules are invented regarding how much food is allowed and how much exercise is needed after eating certain amounts of food
• Those suffering from anorexia pursue a very low 'ideal' weight The weight loss may cause hormonal disturbances and women with anorexia nervosa may stop having periods

The cause of anorexia nervosa is unknown, although it is likely that both inherent biological factors and factors in the patient's social environment play a part. The disease is mainly encountered in the western world and is more common among women in certain professions, such as models and ballet dancers. Puberty, deaths in the family and other life stresses are all believed to be potential triggers of anorexia.

• 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 drugs (drugs that make you urinate more) laxatives, diet pills or vomiting.
• Sometimes people make themselves sick to lose weight. Others indulge in 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

• People who do not receive treatment may become chronically ill or even die
• Long spells without adequate intake of food can cause osteoporosis (fragile bones) and damage to the heart, liver, kidneys and brain
• Aneroxia can impede growth in the young and cause difficulties in concentrating
• People with anorexia nervosa may also experience mental health problems such as depression and increased risk of suicide

• Restore the person to a healthy weight Restore healthy eating patterns
• Treat any physical complications or associated mental health problems
• Address thoughts, feelings and beliefs concerning food and body image
• Enlist family support In some cases, medication is necessary, especially where there is depression or serious compulsive symptoms.
• Treatment by the family doctor is possible, although sometimes a psychologist or psychiatrist, experienced in eating disorders may need to be consulted.
• If the weight loss becomes serious (more than 20 - 25 percent less than total normal body weight), admission to hospital may be required. Treatments used include individual psychological therapy, family therapy and drug therapy with anti-depressants.