Separating anorexia from bulimia on the exam
Anorexia nervosa involves restriction of intake leading to significantly low body weight, an intense fear of gaining weight and a distorted body image. The physical findings follow from starvation: bradycardia, hypotension, hypothermia, dry skin, lanugo, brittle hair and nails, amenorrhoea, constipation and, over time, osteoporosis. Laboratory values may show anaemia, leukopenia, low potassium and abnormal thyroid studies.
Bulimia nervosa involves recurrent binge eating followed by compensatory behaviours such as self-induced vomiting, laxative misuse or excessive exercise. Body weight is often normal, which is why the diagnosis is missed clinically and why the exam gives you physical clues instead: enamel erosion and dental caries, parotid gland enlargement, calluses or scarring on the knuckles from inducing vomiting, oesophageal irritation and electrolyte disturbances.
The shared danger is electrolyte loss. Repeated vomiting produces hypokalaemia and metabolic alkalosis; laxative abuse produces hypokalaemia with metabolic acidosis. In both, a potassium below the normal range with cardiac symptoms is the finding to report first, because dysrhythmias, not weight, are what kill these clients.
| Feature | Anorexia nervosa | Bulimia nervosa |
|---|---|---|
| Body weight | Significantly low | Often normal or slightly above |
| Core behaviour | Restriction, excessive exercise | Binge then purge |
| Skin and hair | Lanugo, dry skin, hair loss | Usually normal |
| Mouth and hands | Usually normal | Enamel erosion, parotid swelling, Russell's sign |
| Vital signs | Bradycardia, hypotension, hypothermia | Often normal between episodes |
| Key lab risk | Hypokalaemia, anaemia, low albumin | Hypokalaemia, metabolic alkalosis |
| Insight | Often denies a problem | Often aware and ashamed |
Refeeding syndrome
Refeeding syndrome is the most commonly missed item in this content area. When a severely malnourished client begins receiving carbohydrate again, insulin secretion resumes and drives phosphate, potassium and magnesium into the cells. Serum levels fall abruptly, and the result can be cardiac dysrhythmias, heart failure, respiratory failure, seizures and death, usually within the first three to five days of feeding.
Prevention is why nutrition is advanced slowly rather than generously. Calories are increased gradually, electrolytes including phosphate are checked daily during the early phase, thiamine is replaced before or with the first feeds, and cardiac monitoring is used for the highest-risk clients. Fluid balance and daily weights are tracked because rapid weight gain in the first days reflects fluid, not tissue.
On the exam, a stem describing a newly admitted client with severe anorexia who develops confusion, weakness or dysrhythmias two days after nutrition was started is describing refeeding syndrome. The correct answer will involve checking or reporting electrolytes rather than encouraging more intake.
- •Highest risk in the first 3–5 days of refeeding
- •Phosphate is the classic falling electrolyte; potassium and magnesium follow
- •Advance calories slowly and monitor labs daily
- •Give thiamine before or alongside the first feeds
- •Watch for oedema, dysrhythmias, weakness and confusion
Mealtime nursing interventions
Structure is the intervention. Correct answers consistently include supervising meals, setting a defined time limit for eating, remaining with the client during the meal and for at least one hour afterward to prevent purging, monitoring bathroom access after eating, weighing the client at the same time each morning after voiding while wearing similar clothing and often with the client facing away from the scale, and recording intake accurately without bargaining over individual foods.
Distractors usually offer either coercion or collusion. Threatening consequences, arguing about body image, or focusing conversation on food and weight all reinforce the disorder's control dynamic. So does allowing the client to prepare their own meals unsupervised or to exercise freely during the refeeding phase.
Therapeutic communication answers acknowledge feelings without debating perception. Rather than 'you are not fat', which invites argument, the better response names the observation and invites exploration, such as 'you seem distressed after meals — tell me what you are feeling.' Positive feedback is directed at behaviours and coping, not at weight or appearance.
Treatment, comorbidity and long-term goals
Treatment is multidisciplinary: medical stabilization, nutritional rehabilitation with a dietitian, individual and family therapy, and medication where indicated. Cognitive behavioural therapy has the strongest evidence base, and family-based treatment is standard for adolescents. Fluoxetine is approved for bulimia nervosa; bupropion is contraindicated in eating disorders because it lowers the seizure threshold in clients with purging behaviour and electrolyte disturbance.
Depression, anxiety and obsessive-compulsive features are commonly comorbid, and suicide risk is elevated, so a safety assessment belongs in the nursing plan. Hospitalization criteria centre on physiological instability: severe bradycardia, hypotension, dangerous electrolyte values, arrhythmias or a very low percentage of expected body weight.
Long-term goals are measurable and behavioural — maintaining a target weight range, eating a specified number of supervised meals, identifying triggers, and using alternative coping strategies. Practise recognizing which goal is realistic for the acute phase versus rehabilitation, since the exam often asks which outcome is appropriate right now.