The reasoning
Core = restriction of intake → significantly low weight, intense fear of weight gain or behaviours interfering with weight gain, and overvaluation/disturbance of weight/shape (fear may be expressed behaviourally — rigid rules, body‑checking, compulsive exercise — rather than stated). Subtypes: restricting vs binge‑purge.
Medical risk is the priority 🚩
Anorexia has the highest mortality of any psychiatric disorder (starvation complications + suicide). Screen: bradycardia, hypotension, hypothermia, arrhythmia (prolonged QTc), electrolyte derangement (K⁺, PO₄³⁻, Mg²⁺), hypoglycaemia, marrow suppression, osteoporosis, endocrine failure. Use a structured risk tool (e.g., MEED/prior MARSIPAN); severe cases need urgent medical admission.
Refeeding syndrome — anticipate it
Reintroducing nutrition to a starved patient → insulin surge → intracellular shift → hypophosphataemia, hypokalaemia, hypomagnesaemia, thiamine depletion → arrhythmia, seizures, cardiac failure. Mitigate: start low, go slow, supplement thiamine before/with carbohydrate, replace electrolytes, monitor bloods daily initially.
Management
Multidisciplinary: nutritional rehabilitation + eating‑disorder‑focused psychotherapy (FBT/family‑based for adolescents; CBT‑ED/MANTRA for adults) + medical monitoring. Weight restoration is a therapeutic goal; medication is not a sole treatment.
Pitfalls
- Treating it as "psychological only" and under‑monitoring the body.
- Aggressive refeeding precipitating fatal electrolyte shifts.
Pearls
- 🎯 Highest‑mortality psychiatric disorder — physical monitoring is psychiatric care.
- 🩺 Start low, go slow, give thiamine, watch phosphate — the refeeding mantra.
Next → The binge‑purge disorder that hides at normal weight (Concept 34).