Summary

Bulimia Nervosa (BN) is a serious eating disorder characterized by recurrent episodes of binge eating followed by compensatory behaviours to prevent weight gain, including self-induced vomiting, laxative/diuretic misuse, fasting, or excessive exercise. Unlike anorexia nervosa, individuals with bulimia typically maintain a normal or slightly above-normal body weight, which often delays recognition. BN carries significant medical risks including electrolyte disturbances (particularly hypokalaemia), dental erosion, and oesophageal complications. Lifetime prevalence is 1-2% in women, with peak onset in late adolescence. CBT-ED is the first-line treatment with high success rates, and high-dose fluoxetine is an effective adjunctive pharmacotherapy.

Key Facts

• Definition: Recurrent binge eating (at least once weekly for 3 months) with compensatory behaviours
• Prevalence: 1-2% lifetime prevalence in women; 0.1-0.5% in men
• Peak onset: 15-20 years (later than anorexia nervosa)
• Weight: Usually normal BMI (18.5-25) — distinguishes from anorexia nervosa
• Key complication: Hypokalaemia from vomiting (can cause cardiac arrhythmias)
• First-line treatment: CBT-ED (Cognitive Behavioural Therapy for Eating Disorders)
• Medication: Fluoxetine 60mg daily reduces binge frequency by 50%

Clinical Pearls

Russell's Sign: Calluses and scarring on the dorsum of the hand/knuckles from repeated self-induced vomiting. Named after Gerald Russell who first described bulimia nervosa in 1979.

The "Normal Weight" Trap: Unlike anorexia nervosa, patients with bulimia typically have normal BMI. This leads to delayed diagnosis — average delay is 5-10 years. Always ask about eating behaviours regardless of weight.

Electrolyte Pattern: Hypokalaemic hypochloraemic metabolic alkalosis is pathognomonic of vomiting. If you see this pattern unexpectedly, consider covert purging.

Why This Matters Clinically

Bulimia nervosa has significant mortality (standardised mortality ratio 1.9) and morbidity, yet is often undetected due to normal weight and secretive behaviours. Early recognition enables effective treatment — CBT-ED achieves remission in 40-50% and significant improvement in another 30%. Medical complications including cardiac arrhythmias from hypokalaemia are preventable with timely intervention.

Structured Approach

General:

• Weight and BMI (usually normal 18.5-25)
• Vital signs: postural BP drop, tachycardia
• Hydration status: mucous membranes, skin turgor

HEADSSS Assessment (Adolescents):

• Home, Education, Activities, Drugs, Sexuality, Suicide/self-harm, Safety

Oral Examination:

• Dental erosion (lingual surfaces of upper incisors)
• Parotid swelling (bilateral, non-tender)
• Pharyngeal erythema

Hands:

• Russell's sign (calluses on knuckles)
• Peripheral oedema

Cardiac:

• Heart rate and rhythm
• Blood pressure (lying and standing)

Mental State Examination:

• Mood (depression, anxiety common)
• Self-harm/suicidal ideation screening
• Body image and weight overvaluation
• Motivation and insight

Special Tests

SCOFF Screening Questionnaire

• S: Do you make yourself Sick because you feel uncomfortably full?
• C: Do you worry you have lost Control over how much you eat?
• O: Have you recently lost One stone (6.35 kg) in a 3-month period?
• F: Do you believe yourself to be Fat when others say you are too thin?
• F: Would you say that Food dominates your life?

Score ≥2 = positive screen; sensitivity 85%, specificity 90%

Natural History

• Without treatment: Chronic relapsing course over years to decades
• Spontaneous remission occurs but is uncommon
• Crossover to anorexia nervosa occurs in 10-15%

Outcomes with Treatment

Prognostic Factors

Good Prognosis:

• Younger age at treatment onset
• Shorter duration of illness before treatment
• Good initial response to CBT
• Higher baseline BMI
• Absence of comorbid personality disorder
• Strong social support

Poor Prognosis:

• Long duration of untreated illness (greater than 5 years)
• Comorbid personality disorder (especially borderline)
• Comorbid substance misuse
• History of childhood abuse
• Severe purging frequency
• Previous treatment failure
• Poor insight

Key Guidelines

1. NICE NG69 (2017) — Eating disorders: recognition and treatment. Recommends CBT-ED as first-line for bulimia nervosa; fluoxetine 60mg as adjunct. NICE NG69
2. RANZCP Clinical Practice Guidelines (2014) — Australian/NZ guidance on eating disorders. RANZCP
3. APA Practice Guideline for Eating Disorders (2023) — American Psychiatric Association updated guidance. APA

Landmark Trials

NICE CBT-BN Review (2017) — Systematic review informing NICE guidance

• Multiple RCTs pooled
• Key finding: CBT-ED superior to other psychological therapies and pharmacotherapy alone
• Clinical Impact: Established CBT-ED as gold standard

Fluoxetine Bulimia Nervosa Collaborative Study (1992)

• 387 patients randomised to fluoxetine 20mg, 60mg, or placebo
• Key finding: Fluoxetine 60mg reduced binge frequency by 51% vs 29% placebo
• Clinical Impact: Established high-dose fluoxetine as effective adjunct

Fairburn et al. (2009) — Transdiagnostic CBT for eating disorders (CBT-E)

• Demonstrated that enhanced CBT protocol effective across eating disorder diagnoses
• Clinical Impact: Led to development of CBT-ED as unified treatment approach

Evidence Strength

What is Bulimia Nervosa?

Bulimia nervosa is an eating disorder where a person gets caught in a cycle of eating large amounts of food (called a "binge") and then trying to get rid of the food or its effects (called "purging"). Purging might involve making yourself sick, using laxatives, or exercising excessively. People with bulimia are often a normal weight, which can make the condition harder to spot.

Why does it matter?

Bulimia is not just about food — it is a serious mental health condition that affects your emotional wellbeing and can cause physical harm. Making yourself sick repeatedly can cause your body to lose important minerals, especially potassium, which is vital for your heart. It can also damage your teeth, throat, and digestive system. Many people with bulimia also struggle with depression and anxiety.

How is it treated?

1. Talking therapy (CBT): The most effective treatment is a type of therapy called CBT for eating disorders. This helps you understand the thoughts and feelings that lead to binge eating and purging, and develop healthier ways of coping. It usually involves 16-20 sessions.
2. Guided self-help: For milder cases, you might start with working through a self-help book or app with some support from a therapist.
3. Medication: An antidepressant called fluoxetine (Prozac) at a higher dose can help reduce the urge to binge eat.
4. Nutritional advice: Learning to eat regular, balanced meals rather than restricting then binging.

What to expect

• Treatment works for most people — about 40-50% will fully recover, and another 30% will get much better
• It takes time — expect treatment to last 4-6 months at minimum
• Relapses can happen, especially at stressful times, but you can get back on track
• Your physical symptoms (tiredness, bloating) will improve as the binge-purge cycle stops

When to seek help

See a doctor urgently if:

• You feel dizzy, faint, or your heart is racing or skipping beats
• You have blood in your vomit
• You have severe muscle weakness or cramps
• You are having thoughts of harming yourself
• You feel unable to stop purging despite wanting to