Anorexia Nervosa

•    Core features:

o    BMI <17.5 kg/m² (or <85% expected weight).

o    Intense fear of weight gain, even when underweight.

o    Body image distortion: perceive self as overweight.

o    Amenorrhoea (loss of menstrual periods) common but no longer required for DSM-5 diagnosis.

•    Physical complications:

o    Electrolyte disturbances: especially hypokalaemia (vomiting/laxatives), hypophosphataemia.

o    Osteoporosis (due to low oestrogen and nutritional deficiency).

o    Bradycardia, hypotension, lanugo (fine hair), peripheral oedema.

o    Raised liver enzymes, impaired glucose tolerance, pancytopenia.

•    Refeeding syndrome:

o    Sudden shift to anabolic metabolism → hypophosphataemia, hypomagnesaemia, hypokalaemia.

o    Can cause cardiac failure, seizures.

•    Treatment:

o    Nutritional rehabilitation is first-line (structured meal plan).

o    CBT, especially CBT-E (enhanced version), shown to improve outcomes.

o    Family-based therapy particularly helpful in adolescents.

o    Monitor for medical instability: consider admission if BMI <13, electrolyte disturbances, cardiac arrhythmias.

Bulimia Nervosa

•    Core features:

o    Recurrent binge eating episodes, followed by compensatory behaviours (vomiting, laxatives, excessive exercise).

o    Usually normal or slightly overweight BMI.

•    Physical signs:

o    Electrolyte disturbances: hypokalaemia, metabolic alkalosis.

o    Russell’s sign: calluses on knuckles from induced vomiting.

o    Parotid gland enlargement (sialadenosis), dental enamel erosion.

•    Treatment:

o    CBT is first-line; focuses on normalising eating patterns, challenging distorted thoughts.

o    Fluoxetine (higher doses, e.g., 60 mg/day), reduces binge-purge cycle.

o    Hospital admission if severe electrolyte disturbance, risk of arrhythmia.

Binge-Eating Disorder

•    Core features:

o    Recurrent binge eating without compensatory behaviours.

o    Episodes involve loss of control, eating rapidly, eating alone due to embarrassment, marked distress.

•    Associated features:

o    Often leads to obesity and related metabolic complications (T2DM, hypertension).

•    Treatment:

o    CBT remains first-line.

o    SSRIs may help reduce binge frequency.

o    Address obesity and comorbid mood disorders.

Extra Revision Pearls

•    In anorexia, persistent bradycardia (<50 bpm) or hypotension (<90/60 mmHg) are indications for inpatient care.

•    Avoid rapid refeeding in anorexia → start low-calorie diet, gradual increase with careful electrolyte monitoring.

•    Bulimia has better prognosis than anorexia; more likely to remit fully with treatment.

•    Patients with eating disorders have increased risk of self-harm and suicide; always assess risk.

•    Serum amylase may be raised in bulimia due to vomiting-induced parotid hyperstimulation.