The symptoms of anorexia nervosa include loss of weight and changes in other physical features, together with changes in personality and behaviour.

The physical changes that anorexia nervosa can cause include:

• slow, progressive weight loss, often starting with a normal weight-reducing diet. Children and teenagers with anorexia may still gain weight, but not enough in relation to the normal growth rate for a person of their age,
• stomach pains, swollen stomach and constipation or diarrhoea,
• fainting, dizzy spells and feeling cold,
• downy hair growth on the body,
• dry, rough or discoloured skin,
• hair that thins, breaks or falls out,
• swelling of the hands, feet or face,
• teeth problems, caused by acid from the stomach rotting away the tooth enamel during repeated vomiting,
• insomnia and fatigue,
• loss of bone mass and the onset of osteoporosis (brittle bones) caused by low calcium levels,
• low blood pressure,
• changes to pulse rate and rhythm caused by changes in blood potassium levels, and
• blood changes, including anaemia, low white cell count, plasma and platelet abnormalities.

Women with anorexia often find that their periods stop. Anorexia can cause a loss of libido (sex-drive) in both men and women. In children and teenagers it can delay puberty and cause problems with physical development.

Anorexia nervosa can also cause personality and behavioural changes. A person with anorexia may:

• have an intense fear of gaining weight and a distorted perception of their own body shape - even a normal, healthy body weight may make them feel tense and panicky,
• spend an excessive amount of time in front of a mirror and see themselves as very fat despite visual evidence to the contrary,
• wear baggy clothes to disguise their true weight,
• deny that there is a problem with their weight,
• become depressed,
• experience mood swings,
• become more serious, introverted or restless,
• feel guilty, lose confidence or self-esteem, or become less assertive and more dependent,
• lose interest in their normal activities, becoming focused on their diet,
• develop rituals attached to eating and hiding food,
• over-exercise,
• begin vomiting in secret and/or taking laxatives, or
• use appetite suppressants and/or diuretics.

There is no single cause of anorexia nervosa. It is a complex condition probably caused by a variety of factors.

These factors may include:

• Social pressures to be thin and to be sexually attractive. Anorexia is triggered by weight loss, usually beginning as a normal weight-reducing diet. Young girls may try to conform to unnatural levels of thinness, in a desire not to stand out and so make themselves a target for bullying (in societies which do not associate thinness with sexual attractiveness, eating disorders are rare).
• Research suggests that genetics plays a part in developing an eating disorder. Those with a family history of anorexia appear to be more at risk of developing the condition.
• Personality - there is a tendency for those who develop anorexia to have a conformist, organised and hard-working personality. They may be mildly obsessive and tend towards tidiness.
• Family relationships - the families of anorexics are often high-achieving, with excessive parental control and high expectations of the children.
• Attitudes to stresses occurring outside the home may be a factor. Typical stresses include exam pressures and feelings of rejection arising from difficulties with friends or relationships with members of the same or the opposite sex.
• Research suggests that eating disorders may develop partly in response to difficult life experiences such as sexual or physical abuse, being bullied, or suffering a bereavement while growing up.
• Confusion with sexuality and sexual identity may be a factor, with the individual subconsciously trying to return to the stage before puberty by making themselves smaller and losing their secondary sexual characteristics.
• People who have jobs in which body image or shape is particularly important - such as dancers or models - may be more at risk of developing anorexia.

Diagnosis of anorexia nervosa can be difficult as most people with the condition deny that they are ill and are usually brought to treatment by a family member. Also, anorexia varies in severity between individuals. A person with anorexia may visit their GP because of symptoms such as their periods stopping, abdominal pain, bloating or constipation.

Diagnosis involves an assessment of both psychological and physical factors. It may involve an evaluation of the persons attitude to weight, food, dieting and body image.

A person with anorexia typically weighs at least 15% less than the expected weight for their height and age. Another way of defining anorexia is using Body Mass Index (BMI). A normal BMI for an adult is between 20 and 25. Adults with anorexia have a BMI of less than 17.5.

A doctor will need to rule out other physical conditions such as diabetes and an overactive thyroid gland, which can cause weight loss and other symptoms associated with anorexia.

Anorexia is a serious and complex illness and usually requires specialist medical care.

Guidelines published by the National Institute for Clinical Excellence (NICE) in January 2004 set the standard for NHS treatment of eating disorders in England and Wales.

The main guidelines for the treatment of anorexia nervosa are:

• GPs should make an early diagnosis of an eating disorder so that those seeking help can be assessed and receive treatment at the earliest opportunity.
• Assessment should be comprehensive and include physical, psychological and social needs.
• You should expect to receive most care as an outpatient. You can expect to be offered a number of psychological treatments (including cognitive behavioural therapy (CBT), cognitive analytic therapy (CAT), interpersonal psychotherapy and focal psychodynamic therapy), provided by a specialist in psychological treatment for eating disorders.
• There should be careful monitoring of your physical health to assess your physical risk. Outpatient psychological treatment should normally last at least six months.
• If inpatient treatment is necessary (because you have failed to improve with outpatient treatment or there is a significant risk of suicide or self-harm) it should be in a unit experienced in eating disorders. The unit should be able to provide skilled implementation of re-feeding and careful physical monitoring, as well as a number of psychological treatments from a specialist with experience of treating anorexia nervosa.
• If part of your anorexia involves making yourself vomit, you should be given dental hygiene advice and have regular dental reviews.
• If you are a teenager you should be treated in age-appropriate settings.
• You should be treated near to home, so that you can maintain your social and occupational links.
• If you are a teenager with anorexia nervosa, family members (including other children in the family) should be involved in your treatment and care.
• If you have long-term anorexia nervosa and you are not under the care of secondary care services, you should be offered an annual health review from your GP.

Treatment for anorexia aims to encourage weight gain and healthy eating habits so that the person achieves a normal weight for their age and height. Treatment is usually most effective when the person positively wants to get better. However, as anorexia is often associated with very complex emotional issues, recognising the underlying causes and learning to cope with them can be the most effective way to treat the illness. Specialist eating disorder helplines are available that can offer support and advice - see the Selected links and Support organisations sections of this article for more information.

Occasionally, a person with anorexia may become so weak that they require immediate hospitalisation. Where weight loss is so severe that there is an immediate threat to life, a doctor may use the Mental Health Act 1983 or Children Act 1989 to admit a person with anorexia to hospital against their wishes. Every effort is made to avoid this and it only happens in extreme circumstances. This is sometimes referred to as being sectioned, because a doctor will use a specific section of the Mental Health Act.

If someone is taken into hospital in this way, the hospital will manage their intake of food and fluids. This lack of control can be very distressing to someone with anorexia nervosa and will only be continued as long as healthcare professionals see it as the only way to prevent death.

Other illnesses that occur as a result of anorexia nervosa may need to be treated with medication. In some cases, antidepressant medication may be advised.

Women with anorexia may find it more difficult to become pregnant and are more likely to have premature or low birth-weight babies. For those who develop anorexia before or during puberty, it may delay some of the physical changes of puberty or lead to stunted growth.

Those with anorexia have an increased risk of developing osteoporosis later in life, and anorexia can make muscles - including the heart muscles - lose strength, leading to a greater risk of heart disease in later life.

Anorexia is a serious illness - there is between a 10% and 20% death rate. The most frequent causes of death associated with anorexia are starvation, dehydration, electrolyte (essential minerals in the blood) imbalance, infections, heart failure, and suicide.

The information shown here is Crown copyright and has been reproduced with the permission of NHS Direct. Last updated June 2007.