Eating Disorders

Definition/diagnostic criteria Eating disorders are characterised by abnormal eating habits and a preoccupation with body weight or shape, leading to significant impairment in health or functioning. The main types include anorexia nervosa, bulimia nervosa and binge-eating disorder. Diagnostic criteria include:

• Anorexia nervosa: persistent energy intake restriction, intense fear of gaining weight, and disturbances in self-perceived weight or shape.
• Bulimia nervosa: recurrent episodes of binge eating and compensatory behaviours for bulimia nervosa.
• Binge-eating disorder: recurrent episodes of binge eating without regular use of compensatory behaviours.

Epidemiology Eating disorders predominantly affect young people, particularly females aged 12-20, but they can occur at any age and in both sexes. The lifetime prevalence for anorexia nervosa and bulimia nervosa in women is approximately 1.5% and 1-3% respectively, with binge-eating disorder being more common.

Diagnosis
Clinical features: Symptoms vary depending on the type of eating disorder but often include:

• Preoccupation with food, body weight and shape.
• Drastic weight loss (in anorexia nervosa – BMI is typically less than 18.5).
• Binge eating.
• Purging.
• Excessive exercise.

Psychological symptoms may include anxiety, depression and obsessive behaviours.

Investigations: Diagnosis is primarily clinical, but investigations may be used to assess the impact on physical health. These can include full blood count, urea and electrolytes, liver function tests, thyroid function tests and ECG.

Typical abnormalities might include electrolyte imbalances, particularly hypokalaemia in bulimia nervosa, and bradycardia or QT prolongation in anorexia nervosa.

Treatment Treatment is multidisciplinary and tailored to the individual. Key components include:

• Psychological therapies: Cognitive-behavioural therapy (CBT) is the first-line treatment for adults with bulimia nervosa and binge-eating disorder. For anorexia nervosa, family therapy is often recommended for children and adolescents, and a range of options are considered for adults, including CBT, MANTRA (Maudsley Anorexia Nervosa Treatment for Adults), SSCM (Specialist Supportive Clinical Management) and FPT (Focal Psychodynamic Therapy).
• Pharmacotherapy: Antidepressants, particularly SSRIs, may be used for bulimia nervosa and binge-eating disorder, but are not first-line treatments for anorexia nervosa due to lack of evidence of effectiveness.
• Nutritional support and medical monitoring: Particularly important in anorexia nervosa, involving regular monitoring of weight, physical health and mental state.

Prognosis The prognosis varies widely. Anorexia nervosa has the highest mortality rate of any psychiatric disorder, largely due to medical complications and suicide. Early intervention improves prognosis. Long-term recovery rates are estimated at 50% for anorexia nervosa, 60-70% for bulimia nervosa, and higher for binge-eating disorder.