FFinalistSouthampton · 2027
Psychiatry
AKT · Psychiatry/Eating

Eating disorders

Overview

Anorexia nervosa (restriction → significantly low weight, fear of weight gain, body-image disturbance), bulimia nervosa (binge–purge cycles at normal/above weight), and binge-eating disorder.

Recognise

  • Anorexia: low BMI, amenorrhoea, lanugo, bradycardia/hypotension, cold intolerance
  • Bulimia: normal weight, Russell’s sign, eroded enamel, parotid swelling, hypokalaemia
  • Binge-eating: recurrent binges without compensatory purging

Red flags

  • Anorexia red flags: BMI <13, rapid weight loss, bradycardia <40, hypotension, hypoglycaemia, prolonged QTc, hypokalaemia — consider inpatient/MARSIPAN

Differentials & how to tell them apart

Hyperthyroidism / malignancy / IBDorganic weight loss without body-image disturbance
Depressionappetite loss without weight phobia
Diabetes (new)weight loss with polyuria/polydipsia

Investigations

Weight/BMI, ECG (bradycardia, long QTc, arrhythmia), U&E (hypokalaemia from vomiting/laxatives), phosphate/magnesium (refeeding), glucose, FBC, LFTs, bone density if chronic.

Management

  1. 1Anorexia (adults): individual CBT-ED, MANTRA, or SSCM. Children/young people: anorexia-focused family therapy (FT-AN) first-line.
  2. 2Bulimia: guided self-help (CBT-based) first-line in adults; FT-BN in young people.Gate: If guided self-help is unacceptable/ineffective after 4 weeks → individual CBT-ED
  3. 3Manage medical risk; beware refeeding syndrome — correct and monitor phosphate, potassium, magnesium.
Psychological therapy, not drugs, is first-line — no drug is first-line for anorexia
Fluoxetine — adjunct in bulimia nervosa (higher dose)

Key points

Refeeding syndrome: ↓phosphate/↓potassium/↓magnesium + fluid shifts on reintroducing food — refeed cautiously with monitoring and thiamine. SSRIs less effective in low-weight anorexia.

Monitor & prognosis

Weight, ECG/QTc, electrolytes (esp. phosphate during refeeding), bone health.

Anorexia has the highest mortality of any psychiatric disorder; bulimia better.

Source: NICE CKS Eating disorders (2025) / NG69