Eating disorders
Exam Tips
- In paediatrics, diagnose risk from growth-trajectory collapse and physiological instability, not BMI alone.
- Red flags for urgent admission: bradycardia, postural hypotension/syncope, hypothermia, significant electrolyte abnormality, dehydration, or high suicide risk.
- Atypical anorexia can be medically severe despite normal or high BMI.
- Bulimia exam classic: recurrent bingeing plus compensatory behaviours, Russell sign, dental erosion, hypokalaemia-related ECG changes.
- Refeeding syndrome is a high-yield OSCE topic: monitor phosphate, potassium, magnesium, fluid status, and ECG closely in early refeeding.
- Image correlate for spot diagnosis: Russell sign on knuckles, parotid enlargement, and dental enamel erosion in purging disorders.
Definition
Eating disorders are serious psychiatric illnesses in which persistent disturbance of eating behaviour (restriction, bingeing, purging, or mixed patterns) causes medically significant harm and impaired psychosocial functioning. In children and young people, presentations often evolve over time, so a patient may move between anorexia nervosa, bulimia nervosa, binge-eating disorder, and OSFED/UFED phenotypes rather than fitting one fixed diagnosis.
Pathophysiology
Current models are biopsychosocial. Genetic vulnerability and family loading interact with neurobiological changes (including serotonergic and dopaminergic signalling, altered reward/interoceptive processing, and dysregulated hunger-satiety hormones such as ghrelin) plus psychological traits (perfectionism, compulsivity, impulsivity, anxiety) and sociocultural pressures about body shape/weight. Starvation then reinforces illness biology: hypothalamic suppression causes amenorrhoea and endocrine disturbance; low intake causes bradycardia, hypotension, bone demineralisation, and cognitive slowing; purging drives hypokalaemic metabolic alkalosis and arrhythmia risk. In binge-spectrum illness, repeated binge-restriction cycles and affect dysregulation perpetuate loss-of-control eating and weight-related metabolic morbidity.
Risk Factors
- Female sex (but important rise in boys/young men)
- Adolescence and early adulthood
- Childhood overweight or weight-related stigma
- Family history of eating disorder, psychiatric illness, or substance misuse
- Comorbid anxiety, depression, OCD traits, autism/neurodivergence, low self-esteem
- Perfectionism, body dissatisfaction, overvaluation of weight/shape
- Trauma history (including sexual abuse), household stress, social isolation
- Activities with pressure for leanness (e. g. dance, endurance sport, weight-category sport)
- For binge-eating disorder: food insecurity, poverty, violence exposure
Clinical Features
Symptoms
- Restrictive intake, meal skipping, rigid food rules, calorie counting
- Intense fear of weight gain or persistent drive for thinness
- Binge episodes with loss of control (typically rapid eating, secrecy, guilt)
- Compensatory behaviours: self-induced vomiting, laxative/diuretic misuse, excessive exercise
- Body image distortion or overvaluation of shape/weight
- Fatigue, dizziness/syncope, cold intolerance, constipation, abdominal bloating
- Menstrual disturbance/amenorrhoea, reduced libido, poor concentration
- Mood symptoms, anxiety, irritability, self-harm or suicidality
Signs
- Low BMI or failure to maintain expected growth trajectory in CYP
- Bradycardia, postural hypotension, hypothermia, peripheral oedema
- Dry skin, lanugo hair, alopecia, acrocyanosis/chilblains
- Muscle wasting and reduced power
- Dental enamel erosion, parotid enlargement, halitosis
- Russell sign (dorsal hand calluses from induced vomiting)
- Signs of dehydration or electrolyte disturbance
- Weight fluctuation or obesity in binge-spectrum disorders
Investigations
Management
Lifestyle Modifications
- Early referral to specialist eating-disorder services (CAMHS/community ED team) with family-based, multidisciplinary care
- Nutritional rehabilitation using a structured meal plan and supervised eating support
- Family-based treatment (first-line in children/adolescents), psychoeducation, relapse prevention planning
- Monitor medical risk frequently (vitals, ECG, bloods, hydration, suicidality); escalate to urgent paediatric admission if unstable
- Address comorbidity and safeguarding (self-harm risk, abuse, neglect, school and social functioning)
Pharmacological Treatment
Selective serotonin reuptake inhibitor (for bulimia nervosa, mainly adults/specialist use)
- Fluoxetine 60 mg once daily (BNF adult dose for bulimia nervosa)
Medication is adjunctive, not a replacement for psychological treatment. In under-18s, specialist psychiatric prescribing is required; monitor for agitation/suicidal ideation, hyponatraemia, and interactions. Correct major electrolyte disturbance first because arrhythmia risk is higher in purging states.
Micronutrient support in malnutrition/refeeding risk
- Thiamine 100 mg two to three times daily (oral; regimen tailored locally/specialist advice)
- Multivitamin and trace-element supplementation
Use during refeeding to reduce deficiency-related complications. Refeeding must be gradual with close phosphate, potassium, magnesium, fluid-balance and cardiac monitoring to avoid refeeding syndrome.
Safety/avoidance points
- Avoid bupropion in anorexia nervosa or bulimia nervosa (contraindicated due to seizure risk)
Do not use medication as sole treatment for anorexia nervosa. Avoid drugs that worsen QT prolongation, hypotension, or electrolyte imbalance where possible; review laxative/diuretic misuse and stop safely.
Complications
- Cardiac arrhythmia, hypotension, and sudden cardiac death
- Electrolyte disturbance (especially hypokalaemia), dehydration, acute kidney injury/chronic kidney disease
- Refeeding syndrome during nutritional restoration
- Low bone mineral density, fractures, growth and pubertal delay in children/teens
- Gastrointestinal dysmotility, constipation, reflux, Mallory-Weiss tear or rarely oesophageal rupture (purging)
- Dental enamel erosion and parotid gland enlargement
- Infertility/subfertility, menstrual disturbance, adverse pregnancy outcomes
- Depression, anxiety, self-harm, and suicide
- Social/educational impairment and caregiver burden
Prognosis
Outcome improves with early detection, family involvement, and sustained specialist follow-up. Many young people recover, but relapse is common and risk persists across diagnostic crossover. Anorexia nervosa carries the highest mortality among psychiatric disorders, from both medical complications of starvation and suicide.
Sources & References
🏥BMJ Best Practice(5)
💊BNF Drug References(1)
- Bupropion hydrochloride[contraindications]
✅NICE Guidelines(1)
- Eating disorders[overview]
📖Textbook References(20)
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1078)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 25, 26)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1693, 1694)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1079, 1080)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1049)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1841)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1275)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1688, 1689)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1830)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1276)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1077)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1688)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1077)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1275, 1276)[context]
- David Randall PhD MRCP (Editor), John Booth PhD MRCP (Editor), K - Kumar and Clark's Clinical Medicine (2025, American Elsevier Publishing Co.) - libgen.li.pdf(pp. 1275, 1276)[context]
- _OceanofPDF.com_Netters_Anatomy_-_8th_edition_-_Frank_H_Netter_MD.pdf(pp. 3044)[context]
- _OceanofPDF.com_Netters_Anatomy_-_8th_edition_-_Frank_H_Netter_MD.pdf(pp. 2532)[context]
- [Oxford Medical Handbooks] Ian Wilkinson, Tim Raine, Kate Wiles, Anna Goodhart, Catriona Ha - Oxford Handbook of Clinical Medicine (2017, Oxford University Press) - libgen.li.pdf(pp. 103)[context]
- [Williams, Bailey and Love's Short Practice of Surgery] Norman Williams, Christopher Bulstrode, P Ronan O'Connell - Bailey & Love's Short Practice of Surgery 26E (2013, CRC Press) - libgen.li.pdf(pp. 752, 753)[context]
- [Williams, Bailey and Love's Short Practice of Surgery] Norman Williams, Christopher Bulstrode, P Ronan O'Connell - Bailey & Love's Short Practice of Surgery 26E (2013, CRC Press) - libgen.li.pdf(pp. 753)[context]