A 16-year-old girl has intense cravings for food. She eats large amounts of food, which is followed by self-induced vomiting. What is the probable diagnosis?

Explanation

## Correct Answer: B. Bulimia nervosa Bulimia nervosa is characterized by recurrent episodes of binge eating followed by compensatory behaviors to prevent weight gain. The key discriminating feature in this case is the presence of **both binge eating and self-induced vomiting** (purging). According to DSM-5 criteria (adopted in Indian psychiatric practice), bulimia nervosa requires: (1) recurrent episodes of binge eating (consuming large amounts of food with loss of control), (2) recurrent inappropriate compensatory behaviors (self-induced vomiting, laxative abuse, fasting, or excessive exercise), and (3) self-evaluation unduly influenced by body shape and weight. The patient's presentation—intense food cravings, large food intake, followed immediately by self-induced vomiting—is the classic triad of bulimia nervosa. Unlike anorexia nervosa, patients with bulimia typically maintain near-normal body weight, though they may have electrolyte abnormalities (hypokalemia, metabolic alkalosis) and dental erosion from repeated vomiting. In Indian adolescent populations, bulimia nervosa is increasingly recognized, particularly in urban settings with media-driven body image concerns. The presence of active purging behavior is the critical distinguishing feature from binge eating disorder. ## Why the other options are wrong **A. Binge eating disorder** — Binge eating disorder involves recurrent binge eating episodes but **lacks compensatory purging behaviors**. Patients with BED do not engage in self-induced vomiting, laxative abuse, or fasting to counteract binges. They typically experience guilt and distress but no active purging. The presence of self-induced vomiting in this case definitively excludes BED and points to bulimia nervosa. This is a common NBE trap—students may focus only on the binge eating component and miss the purging behavior. **C. Anorexia nervosa** — Anorexia nervosa is characterized by severe caloric restriction, intense fear of weight gain, and significantly low body weight (BMI typically <17.5 kg/m²). While the binge-eating/purging subtype of anorexia exists, it occurs **only in the context of severe underweight status**. This 16-year-old's presentation does not mention significant weight loss or being underweight. Bulimia nervosa patients maintain near-normal weight despite purging, making this the correct diagnosis when purging occurs without severe underweight. **D. Atypical depression** — Atypical depression features mood symptoms (depressed mood, anhedonia) with atypical features like hyperphagia, hypersomnia, and rejection sensitivity. While increased appetite may be present, **atypical depression does not involve self-induced vomiting or compensatory purging behaviors**. The core feature here is the eating disorder cycle (binge-purge), not a primary mood disorder with secondary appetite changes. Mood symptoms may coexist with bulimia but are not the primary diagnosis. ## High-Yield Facts - **Bulimia nervosa** = binge eating + compensatory purging (vomiting, laxatives, fasting, exercise) with near-normal body weight maintained - **Purging subtype** (self-induced vomiting) causes **hypokalemia, metabolic alkalosis, dental erosion, and parotid gland enlargement** (Russell's sign on knuckles) - **DSM-5 criteria**: ≥1 binge-purge episode per week for ≥3 months; self-evaluation unduly influenced by body shape/weight - **Binge eating disorder** differs by **absence of purging**; anorexia nervosa differs by **severe underweight status (BMI <17.5)** - **Indian adolescent risk**: urban populations, media exposure, perfectionism, and family pressure on appearance increase bulimia nervosa prevalence - **Medical complications**: electrolyte imbalance (life-threatening arrhythmias), esophageal rupture, aspiration pneumonia, and infertility from hormonal disruption ## Mnemonics **BN vs BED vs AN (Eating Disorder Trio)** **BN** = Binge + purge (Normal weight) | **BED** = Binge only (Overweight) | **AN** = Restrict (Underweight). Use when differentiating eating disorders: ask 'Is there purging?' (→BN), 'Is weight low?' (→AN), 'Neither?' (→BED). **Russell's Sign Memory Hook** **R**ussell's sign = **R**aw knuckles from teeth scraping during self-induced vomiting in bulimia. Calluses on dorsal hand surface = classic bulimia finding. Check hands at every eating disorder assessment. ## NBE Trap NBE pairs binge eating with bulimia to lure students into choosing binge eating disorder (which also involves binges but lacks purging). The discriminating feature—**self-induced vomiting**—is the purging behavior that defines bulimia nervosa and must not be overlooked. ## Clinical Pearl In Indian clinical practice, bulimia nervosa often presents with dental erosion and electrolyte abnormalities (hypokalemia causing palpitations) before patients disclose purging behavior. Always screen for self-induced vomiting, laxative abuse, and diuretic misuse in adolescents with binge eating complaints—these purging behaviors define bulimia and require urgent medical monitoring for cardiac and renal complications. _Reference: DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, 5th Edition); Harrison's Principles of Internal Medicine Ch. 385 (Eating Disorders); Indian Psychiatric Society Guidelines on Eating Disorders_