Overview
Serious mental illnesses with serious medical complications.
Eating disorders are psychiatric illnesses involving a disturbed relationship with food, eating, and body image — but they cause very real, sometimes life-threatening medical complications. They most often begin in adolescence and frequently occur alongside depression, anxiety, and OCD.
- Anorexia nervosa — restriction and significantly low weight
- Bulimia nervosa — binge eating + compensatory behaviors
- Binge-eating disorder — binges without compensation
Anorexia nervosa has the highest mortality rate of any psychiatric illness, mostly from cardiac and electrolyte complications and suicide. That's why eating disorders are treated as both a mental-health and a medical priority — the nurse watches the heart and electrolytes as closely as the behavior.
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Anorexia Nervosa
Restriction, low weight, and an intense fear of gaining.
Anorexia nervosa is defined by three features:
- Restriction of intake leading to a significantly low body weight
- Intense fear of gaining weight or becoming fat
- Distorted body image — sees self as overweight despite being underweight; often denies the seriousness
There are two subtypes: restricting type and binge-eating/purging type. Clients may exercise excessively and use rituals around food.
For many clients, restricting food is a way to feel in control. Recognizing this helps the nurse avoid power struggles — the goal is to build trust and restore nutrition safely, not to "win" battles over eating.
Bulimia Nervosa
Binge, then compensate — often at a normal weight.
Bulimia nervosa involves recurrent binge eating (eating a large amount with a sense of loss of control) followed by compensatory behaviors to prevent weight gain:
- Self-induced vomiting, laxatives, or diuretics
- Fasting or excessive exercise
- Clients are usually at or near a normal weight, so it is often hidden
Physical Signs of Purging
- Russell's sign — calluses/scars on the knuckles (from the teeth)
- Dental erosion and cavities from stomach acid
- Swollen parotid glands ("chipmunk cheeks") and sore throat
Frequent vomiting loses stomach acid and potassium, causing hypokalemia and metabolic alkalosis. Low potassium can trigger dangerous cardiac arrhythmias — making electrolyte monitoring a top nursing concern in bulimia.
Binge-Eating Disorder
Binges without the compensation.
Binge-eating disorder involves recurrent episodes of eating large amounts of food with a sense of loss of control and distress afterward — but without the compensatory behaviors (no purging, fasting, or over-exercising). Clients are often overweight or obese and may eat when not hungry, eat quickly, and feel guilt or shame.
Binge-eating disorder is the most common eating disorder. Because there is no purging, the medical risks are tied to obesity (diabetes, hypertension, heart disease) rather than the acute electrolyte dangers seen in bulimia, but the psychological distress is just as real.
Medical Complications
Why these are medical emergencies, not just behavioral problems.
- Anorexiastarvation
- Bradycardia, hypotension · Cardiac arrhythmias · Amenorrhea (no periods) · Osteoporosis · Hypothermia · Lanugo (fine downy hair)
- Bulimiapurging
- Hypokalemia, metabolic alkalosis · Cardiac arrhythmias (from low K⁺) · Dental erosion, parotid swelling · Esophageal tears (Mallory-Weiss) · Russell's sign on knuckles
In both disorders, the most life-threatening problems are cardiac — arrhythmias from electrolyte imbalance and, in anorexia, a weakened heart from severe malnutrition. Vital signs and electrolytes (especially potassium) are monitored closely.
Refeeding Syndrome
The danger of refeeding too fast.
Refeeding syndrome is a potentially fatal complication that can occur when nutrition is reintroduced too quickly to a severely malnourished client. As feeding resumes, a surge of insulin drives phosphorus, potassium, and magnesium into the cells, dropping their blood levels sharply.
- Most notable is hypophosphatemia (low phosphorus)
- Can cause cardiac arrhythmias, heart failure, and respiratory failure
- Prevention: refeed slowly and monitor electrolytes closely (especially phosphorus, potassium, magnesium)
The safest approach to restoring nutrition in a severely malnourished client is to start with modest calories and advance slowly while watching the electrolytes. A rapid jump in intake is exactly what triggers refeeding syndrome.
Mealtime Nursing Care
Structure, supervision, and trust — without power struggles.
- Structured, supervised meals with a set time and observed portions
- Stay with the client during the meal and ~1 hour after to prevent purging or hiding food
- Monitor weight consistently (often same time daily, in a gown; sometimes with the client's back to the scale to reduce fixation)
- Monitor electrolytes and vital signs, especially potassium and cardiac status
- Avoid power struggles over food; be matter-of-fact, supportive, and non-judgmental
- Often a behavioral contract links privileges to weight restoration and intake goals
Confrontation and bargaining over each bite backfire. A calm, consistent, trusting nurse-client relationship — with clear, firm structure — does more to restore healthy eating than arguing ever will.
? After a supervised meal, a client with bulimia asks to use the bathroom immediately. What should the nurse do?
Therapeutic Approach
A team effort built on therapy and trust.
- Multidisciplinary team — nursing, medical, dietitian, and mental-health providers
- Cognitive behavioral therapy (CBT) to address distorted thoughts about food and body image
- Family-based therapy is especially effective for adolescents
- Address the distorted body image and the underlying anxiety/perfectionism gently and consistently
Nutritional rehabilitation restores the body, but lasting recovery requires addressing the thoughts and emotions driving the disorder. That's why therapy (especially CBT) is central — medication and meals alone rarely fix it.
Key Medications
SSRIs lead — and one drug to avoid.
- Fluoxetine (Prozac)
- SSRI; FDA-approved for bulimia; also treats comorbid depression/anxiety/OCD
- Other SSRIs
- Treat the depression and anxiety that commonly accompany eating disorders
- Electrolyte replacement
- Correct potassium, phosphorus, magnesium as needed
- Bupropion — AVOID
- Contraindicated in clients who purge — increases seizure risk
Anchor on the contrasts: anorexia = underweight + starvation complications (bradycardia, lanugo, amenorrhea); bulimia = normal weight + purging clues (Russell's sign, low potassium, dental erosion). Watch the heart and potassium, refeed slowly, avoid power struggles, and remember fluoxetine for bulimia.
Frequently Asked Questions
Common student questions on this topic.
What is the difference between anorexia and bulimia?
What is refeeding syndrome?
What are the physical signs of bulimia from purging?
Why is anorexia nervosa so dangerous?
What is the nurse's role during meals for a client with an eating disorder?
What medications are used for eating disorders?
Quick-Reference Cheatsheet
Every key point from this guide on a single printable page.
Eating Disorders Cheatsheet
One-page PDF — free download.