Eating disorders

1. Epidemiology and aetiology
Anorexia nervosa and bulimia nervosa are the most recognised eating disorders, but other diagnostic categories include binge-eating disorder and eating disorder not otherwise specified (EDNOS).

Eating disorders affect around 30 per 100,000 of the total population with up to 2 per cent of young women thought to have full-syndrome eating disorders.

Aetiological factors include excessive value placed on thinness and dieting in society, genetics and charac- teristic personality traits, including perfectionism, extreme compliance and negative self-evaluation.

Co-morbidity with other psychiatric conditions may occur, including substance misuse and personality disorders.

Family issues are historically considered relevant, with a stereotype of enmeshed, rigid, overprotective families being linked with anorexia and families considered to have poor boundaries and unable to resolve conflicts linked to bulimia. However, families should not be blamed for causing it.

Bulimia has been widely studied and has a robust evidence base for treatment. However, despite the significant suffering, morbidity and cost inflicted by anorexia, little progress has been made with evidence-based treatments and recommendations. 

Recent NICE guidance for anorexia is predominantly the result of expert consensus. 

Key components of an eating disorder history

  • General history of eating difficulties including length and nature of illness. 
  • Typical day’s food intake.
  • Concerns about weight and shape.
  • Menstrual history.
  • Weight history.
  • Current height and BMI.
  • Co-morbid illness including depression, anxiety disorders, substance misuse, deliberate self-harm and obsessive compulsive disorder.
  • Binge-eating – loss of control, frequency, amount.

2. Diagnosis

The essential feature of anorexia is low body weight controlled by restrictive eating practices: patients do not truly lack appetite but instead struggle to control urges to eat.

Anorexia is typically considered if a patient’s BMI falls below 17.5.

Apart from low body weight, other physical signs include amenorrhoea, which can lead to osteoporosis, and muscle weakness.

Be aware of atypical presentations. Although generally considered a condition associated with puberty, a female patient developing anorexia in her 30s is not uncommon.

The essential feature of bulimia is recurrent binge eating, usually associated with a subjective sense of loss of control.

Binges may be associated with self-induced vomiting or laxative abuse.

Two sub-types of bulimia exist: purging (by far the most common) and non-purging (in which the patient binges and then fasts and exercises).

A diagnosis of bulimia depends entirely on the patient’s history.

Physical signs to be aware of include enlarged parotid glands and calluses on the backs of the fingers and hands (Russell’s sign). 

DSM-IV criteria for anorexia nervosa

  1. Refusal to maintain body weight at or above a minimally normal weight for age and height — weight loss leading to maintenance of body weight less than 85 per cent of that expected; or failure to make expected gain during period of growth, leading to body weight less than 85 per cent of that expected.
  2. Intense fear of gaining weight or becoming fat, even though the patient is underweight.
  3. Disturbance in the way in which one’s body weight or shape is experienced, undue influence of body weight or shape on self-evaluation, or denial of the seriousness of current low body weight.
  4. In postmenarchal females, amenorrhoea.


  • Restricting — during the current episode a person has not regularly engaged in binge eating or purging behaviour.
  • Purging — a person has regularly engaged in binge-eating or purging behaviour (self-induced vomiting, laxative, diuretic or enema use). 

3. Management
Anorexia and bulimia differ in their physical complications and treatment approaches. In general, treatment should address both overt eating behaviour but also wider holistic issues.

Although imprecise, BMI is generally accepted as a reasonable initial estimate of a patient’s physical state of health. Apparent co-morbid psychiatric conditions such as low mood or obsessive features tend to remit with increased weight.  

Anorexia carries the highest medical risk. Consequently, dependant on medical risk and the chronicity of the low weight and nutritional status, patients should be regularly monitored. In practice this falls to primary care. Regular reviews should always include a weight check and calculation of BMI. 

Caution is needed if prescribing psychotropic drugs, because of possible cardiac complications.

The majority of patients with anorexia are managed as out-patients. However, once the medical risk becomes of significant concern, serious consideration should be given to specialist in-patient treatment.

The Mental Health Act can be used to treat anorexia, but this should only be undertaken with specialist input.

Bulimia is mainly treated through out-patient services and has a greater evidence-base for treatment approaches.

The mainstays of treatment are cognitive behavioural therapy (CBT) and antidepressants. Interpersonal therapy (IPT) has also proved to be effective.

However, many patients drop out of therapy and often have underlying co-morbid issues, such as impulsivity and substance misuse.

Treatment for bulimia tends to follow a stepped care model. This starts with self-help material, guided self-help or computer-based training then CBT groups or individual CBT.

Medication can be introduced at any point and current evidence and practice suggests the use of SSRIs, typically at higher doses of up to 60mg per day. The condition tends to relapse once medication is withdrawn and remission rates on medication alone are relatively low at around 25 per cent.

In combination with CBT, recovery is around 50–70 per cent. Medical risk in the majority of normal weight patients with bulimia is relatively low unless purging behaviour is extreme. Electrolytes need to be regularly monitored dependant on the frequency of purging.

With appropriate treatment, eating disorders can be successfully treated ,  generally with specialist intervention. In the absence of such specialist help, local voluntary agencies or national networks (such as BEAT, formerly the Eating Disorders Association) can offer support. Primary care  remains the main source of treatment. 

Eating disorders awareness week runs from 4–10 February. Visit

Side-effects of anorexia nervosa

  • Cardiovascular: hypotension; bradycardia; arrhythmias; prolonged QT interval.
  • Metabolic: hypokalaemia; hyponatraemia; hypomagnesaemia; hypocalcaemia; hypothermia; re-feeding oedema; metabolic alkalosis.
  • Musculo-skeletal: osteoporosis; rhabdomyolysis.
  • Endocrine: amenorrhoea; lowered testosterone.  
  • Gastro-intestinal: oesophagitis; acute gastric dilatation; parotid enlargement; dental erosion.
  • Haematological: neutropaenia; anaemia; thrombocytosis.
  • Dermatological: skin breakdown; dry skin; lanugo hair; purpuric rash.

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