AN Binge-Purge Subtype — MRCPsych Paper B MCQ

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ModerateEating DisordersAN Binge-Purge SubtypeMRCPsych Paper B

A 25-year-old woman has maintained a BMI of 17 kg/m² through persistent dietary restriction and self-induced vomiting. She has recurrent episodes of loss-of-control eating followed by purging and believes that she is overweight despite her low weight. According to ICD-11, what is the most likely diagnosis?

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Correct answer: C — Anorexia nervosa, binge-purge pattern

The diagnosis is **anorexia nervosa, binge-purge pattern**. Her significantly low BMI is maintained by persistent weight-reducing behaviours, and she overvalues or inaccurately perceives her low weight. Recurrent binge eating and purging specify the binge-purge pattern. Bulimia nervosa is the main distractor, but under ICD-11 its symptoms must not meet the definition of anorexia nervosa; it does not strictly require normal or above-normal weight. Binge-eating disorder excludes regular compensatory purging. Atypical anorexia nervosa is used when the anorexia-like syndrome does not include significantly low weight, despite substantial weight loss. ARFID is inconsistent with the prominent weight-and-shape psychopathology. BMI should not be interpreted alone, but here the full syndrome is provided.

Reference: Jafar W, Morgan J. Anorexia nervosa and the gastrointestinal tract, Table 1: ICD-11 comparison of anorexia nervosa and bulimia nervosa. Frontline Gastroenterology. 2022;13:316–324. https://fg.bmj.com/content/13/4/316