An expert’s guide to eating disorders

    21 February 2015


    What are eating disorders?

    Eating disorders are characterised by abnormal attitudes towards food that lead to a change in eating habits and behaviour. The main eating disorders are anorexia nervosa, bulimia nervosa and binge-eating disorder.

    Sufferers with anorexia nervosa restrict their diet and lose significant amounts of weight. Those with bulimia nervosa have bouts of binge eating followed by compensatory purging, usually by laxative abuse or vomiting. In binge-eating disorder, individuals overeat in binges but do not purge. People who binge eat regularly usually put on a great deal of weight.

    In anorexia nervosa there is a preoccupation with eating and body weight. Those affected tend to invest weight with abnormal significance and often experience anxiety when eating; sometimes, but not always, they overestimate their body size. Anorexia nervosa is diagnosed when weight has fallen through dieting below a BMI of 17.5 (BMI — body mass index — is weight divided by height squared, i.e. weight adjusted for height. Ideal BMI is between 18.5 and 25; a BMI of above 25 is classed as overweight.)

    People with bulimia nervosa can be of normal weight and therefore their symptoms often go unrecognised. The episodes of bingeing and vomiting frequently occur in secret. The conditions often overlap and people can start with symptoms of anorexia and later develop bulimic symptoms. Some people have an atypical eating disorder where they have some, but not all, of the typical features of anorexia or bulimia.

    Do these conditions have any common features?

    Using the intake of food as a means of coping with stress or mood disturbance is a shared characteristic of all the eating disorders. People with anorexia have a powerful sense of agency over their bodies when they control their sensation of hunger. This can be a huge relief if external events are anxiety-provoking and out of their control. In treatment, if dietary restraint is relinquished, then it is essential to find other ways of coping with these difficulties. It follows that patients undergoing treatment for anorexia usually feel worse in the initial stages of treatment, until they have been helped to find other ways of dealing with their feelings.

    People with bulimia often have a phase of dieting but they cannot maintain it and eventually ‘rebound’ into binge eating. Binge eating can be provoked by stressful situations and has immediate anxiety-relieving effect. This is quickly followed by anxiety about potential weight gain that, in turn, is relieved by purging, through vomiting or excessive laxative use. The diagnosis is made when these behaviours occur at least once per week.

    Additionally, individuals with anorexia and bulimia are often keen to exercise as a way of controlling their weight.

    People are diagnosed with binge-eating disorder if they overeat in binges, on average, at least once a week for an extended period of at least three months. The binge occurs in a discrete period of time when a large quantity of food is consumed. There are feelings of lack of control and sufferers usually feel guilty afterwards. The triggers are often the same as for bulimia but they suffer the additional perceived humiliation of weight gain. A depressed mood is particularly associated with binge-eating disorder but can occur with all the eating disorders.

    How common are the eating disorders?

    The rates for anorexia are approximately one in 250 women and one in 2,000 men. The condition usually first develops in the teen years. Bulimia is around five times more common than anorexia and usually develops at a slightly later age.

    Binge eating seems to affect males and females equally and most commonly first appears in the thirties. Up to 50 per cent of patients undergoing bariatric surgery (gastric operations for weight loss) have binge-eating disorder.

    What are the complications?

    For anorexia, the complications are those associated with starvation. Females lose their periods and eventually become deficient in vitamins and minerals. They lose muscle strength, although only at a late stage of the illness, and their heart functioning is at risk. Their bones become demineralised and there is an increased risk of fracture. Those who have sustained low weight are at risk of further physical deterioration should they pick up an infection. The microbes causing the infection use up additional calories and in these circumstances there can be a significant deterioration.

    Anorexia has the highest mortality of any mental illness and the outcome is worse if alcoholism is an accompanying disorder.

    In bulimia the main complication is the biochemical abnormity that occurs as a result of purging, especially self-induced vomiting. The blood level of potassium falls and, as potassium is involved in its electrical conduction, this puts the heart at risk. If a patient has hypokalaemia (low potassium), she can experience palpitations and there is a risk of cardiac arrest. In milder cases, the main complications of vomiting are the enlargement of the salivary glands in the cheeks (hamster cheeks) and tooth decay from stomach acid.

    In binge-eating disorder the main complication is obesity with its own health risks.


    For anorexia, the other causes of low weight should be excluded e.g. thyroid disease or, rarely, adrenal gland insufficiency (Addison’s disease). In addition, patients with depression often suffer loss of appetite and lose weight. What distinguishes them from patients with an eating disorder is that they do not have the preoccupation with weight and shape and fear of eating that is so characteristic of anorexia. Patients at low weight should have a check made of their bone density (a DEXA scan). There is a simple test of muscle strength — the ability to rise unaided from squatting — that indicates possible physical decompensation.

    For bulimia, the blood electrolytes should be checked to exclude hypokalaemia.

    For binge-eating disorder, a check should be made of medical causes of weight gain. Drugs such as steroids, anti-hypertensives, anti-psychotics and insulin can be associated with weight gain.

    Treatment options

    For anorexia, the majority of patients respond to outpatient treatment where attention is paid to obvious triggering factors. In adolescents, these include peer relationships, exam pressures, low self-esteem and stresses in the family. This, combined with a structured approach to increase dietary intake, is usually effective. Younger patients can be helped with family therapy where the focus is to explore relationships and find solutions to conflict at mealtimes.

    A minority of patients have a more severe and enduring form of the illness. They have sometimes experienced traumatic events in the past. These patients may require inpatient treatment to halt weight loss and more intensive treatment to ensure weight gain.

    In addition, different psychological approaches have been tried and can be useful but there is no one form of treatment that is particularly beneficial. What is most important is that the therapist should have experience of eating disorders. Patients disengage from treatment with doctors, nurses and therapists who lack experience of treating the condition.

    Bulimia is usually treated with cognitive behavioural therapy (CBT) and response to treatment is very favourable. More complex cases, especially where there are additional complicating mood or personality factors, require more specialised psychological treatment. In some areas CBT is available through the GP but specialist psychological treatment is usually only available from specialist eating disorder units.

    Binge-eating disorder can also be treated with CBT, often provided on a group basis. The binge eating responds well to psychological treatment but overweight is usually unaffected and will require management separately.

    Medication may be used to treat bulimia or binge eating. An SSRI (selective serotonin reuptake inhibitor) can be a useful adjunct to psychological treatment.

    Eating disorders in rarer groups

    Although anorexia is ten times less common in men than in women, the presentation is similar as is the response to treatment. There are a few differences. Males are more likely to have a history of obesity, predating the development of the eating disorder. Men and boys with eating disorder tend to have the ideal of a weight lifter’s body shape. There is said to be a higher frequency of eating disorder in the gay male population. In addition, males with weight concerns are more involved in excessive exercise than females. When exercise continues in spite of injury, this has been described as an ‘activity disorder’. If the populations with eating disorders and activity disorders are added together, the sex difference narrows.
    Older patients
    When anorexia was first described, it was believed that it could not occur for the first time in those aged over 35. This is not the case but late onset is still uncommon. Marital difficulties are often triggering factors in the older patient. They may present with the first occurrence of symptoms, re-emergence of symptoms, increased awareness and distress associated with persistent mild symptoms or significant enduring symptoms for which they have never before sought help. The cumulative effects of many years of disordered eating may have eventually precipitated a health crisis.
    In common with anorexia, psychological profiles of athletes have shown features of perfectionism, competitiveness, hyperactivity, repetitive exercise routines, compulsiveness, tendency toward depression, body image distortion and a preoccupation with dieting and weight.

    Elite athletes have significantly higher rates of eating disorders compared with control groups. The highest rates are in the aesthetic sports of gymnastics, ballet and figure skating.

    What should you do if you are concerned about someone who may have an ED?

    With anorexia, the difficulty is that sufferers may not acknowledge that there is a problem. It is important nevertheless to persuade them to see their GP. A good GP will be sensitive to the problem and refer on for specialists’ help. If the GP is dismissive of the problem and just advises to eat more, patients are unlikely to seek help again until the situation is severe.

    Relatives or carers can contact Beat, the main charity concerned with eating disorders, who can point them to support groups in their area. These groups offer general advice and specific support for families. There are also self-help books and websites that have useful information.

    For sufferers with bulimia there is often relief in disclosing the symptoms to an empathic and experienced professional. A good outcome is often linked with being in a non-judgmental, supportive relationship.


    Anorexia nervosa was first properly recognised in the UK in 1873 and it was in this country that bulimia nervosa was first described 1979. The UK has always been at the forefront of treatment and research into eating disorders. We are fortunate that the treatment that is available in the UK is among the best in the world.