Psychiatric-Mental Health Nursing · Eating Disorders
Anorexia Nervosa
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Anorexia nervosa Eating disorder of energy restriction, fear of weight gain, and disturbed body experience Full entry → is a serious psychiatric eating disorder with three defining features: (1) restriction of energy intake leading to a body weight significantly below what is expected for the person's age, sex, and physical health; (2) intense fear of gaining weight, or persistent behavior that interferes with weight gain; and (3) disturbed experience of body weight or shape — seeing oneself as overweight despite evidence to the contrary, or failing to recognize the seriousness of the low weight. The DSM-5 describes restricting and binge-eating/purging subtypes.
One feature shapes almost everything else: the illness is often Ego-syntonic Illness features that feel consistent with the person's sense of self Full entry → — restriction feels purposeful, even admirable, like control or identity rather than a problem. That is why people minimize symptoms, resist help, and insist they are "fine" while their bodies are in danger. It is not vanity or a diet that got out of hand; it is a disorder with among the highest rates of medical complications and death in psychiatry.
Why this matters
Anorexia nervosa can damage nearly every organ system, and nurses are often the first to notice the warning signs — on a medical-surgical unit where a person is admitted for fainting or an abnormal heart rhythm, in an emergency department, or in school health. Knowing which physical consequences and red flags require immediate escalation can be life-saving. Because people with the disorder often do not believe they are ill, the nursing relationship — trust, consistency, non-judgmental communication — is central to care. On exams, expect questions about the defining features and the differences from other eating disorders; the correct answers involve observation, respectful communication, and reporting per policy.
The college version
Core Concepts
The diagnostic picture
The essential features are restriction leading to significantly low weight, fear of weight gain, and disturbed body experience; severity ratings vary across classification systems. A classic test trap: Amenorrhea Absence of menstruation Full entry → (loss of menstruation) was once required for the diagnosis but was removed from the DSM-5.
The medical footprint of starvation
Starvation affects the whole body: a slow heart rate (bradycardia), low blood pressure, and rhythm disturbances from electrolyte imbalance — especially when purging is present; bone density loss; slowed gut and constipation; and heat conservation via fine downy hair called Lanugo Fine downy body hair that develops in starvation to conserve heat Full entry →, cold intolerance, dry skin, and thinning hair. Nurses do not treat these directly, but recognizing them tells the nurse what to watch for.
The ego-syntonic trap and motivation
Because restriction feels like success to many people with the disorder, motivation is often low, and denial is a symptom rather than dishonesty. A nurse who understands this responds with curiosity and consistency ("It sounds like eating here is really hard for you") instead of accusation. Facility policies on weighing (for example, "blind weights"), meal support, and post-meal observation vary by institution — nurses follow the facility's policy and the provider's orders.
Refeeding risk: recognition and escalation
Refeeding syndrome Dangerous electrolyte shifts when nutrition resumes after starvation Full entry → refers to severe shifts in fluids and electrolytes — particularly phosphorus — as the body switches back to using food after starvation, and it can trigger heart rhythm problems, which is why refeeding is medically supervised and gradual. The nursing role is monitoring and reporting: immediately report palpitations, chest pain, weakness, or swelling, and never adjust feeding regimens on one's own. If a person develops chest pain, faints, or expresses thoughts of self-harm — suicide risk is elevated in anorexia nervosa — the nurse escalates immediately per facility policy.
Classic research worth knowing
The Minnesota Starvation Experiment (1944–1945, led by Ancel Keys) is the classic study here. Thirty-six male conscientious objectors volunteered to be semi-starved for about six months and then refed, so researchers could learn how to rehabilitate starving populations after World War II. Previously healthy men became preoccupied with food, collected recipes, lost interest in socializing, and some developed binge-like eating during refeeding. Context: wartime volunteers, a small all-male sample, experimental starvation in healthy men — not any individual's experience — but the study shows that restriction itself produces many symptoms we associate with eating disorders.
Common Confusions
| Do not confuse | With | Difference |
|---|---|---|
| Anorexia nervosa | Normal dieting or "clean eating" | Anorexia means significantly low weight plus fear of weight gain plus disturbed body image with real medical impact |
| Anorexia nervosa | Bulimia nervosa | Weight: anorexia involves significantly low weight; bulimia usually normal or above-normal weight |
| Anorexia nervosa | ARFID | ARFID involves restriction without fear of weight gain or body image disturbance |
| Restricting subtype | Binge-eating/purging subtype | Both require significantly low weight; they differ by whether binge-purge episodes occur |
| Refusing to eat as defiance | Refusing to eat as an illness symptom | Restriction feels purposeful (ego-syntonic); respond with understanding, not accusation |
| Amenorrhea required for diagnosis | Amenorrhea as one possible sign | DSM-5 removed amenorrhea as a criterion — a common test trap |
Eli explains
The same idea, in plain words
Explain it like I’m 10
Anorexia nervosa is like a person whose brain has a broken alarm: it keeps telling them they must lose more weight to be safe or good enough, no matter how thin they get. Their body gets very sick from not having enough fuel, but the alarm keeps ringing, so they may not see it. It's an illness — not stubbornness or vanity — and it needs professional help.
Worked example
A nursing student is on a medical-surgical rotation when a 19-year-old is admitted for fainting and a slow heart rate. The student notices the patient wears several layers in a warm room, has fine hair on her forearms, pushes food around the tray, and says cheerfully, "I'm fine — I just don't want to gain weight while I'm in here." Her weight is well below what would be expected for her height.
The student's job is not to diagnose, lecture, or bargain ("If you eat dinner, you can have dessert"). Instead she documents what she observes neutrally, reports her concerns to the provider, and speaks without judgment ("It sounds like being asked to eat is really hard for you"). She follows the unit's meal-support and weighing policies and stays alert to red flags — palpitations, chest pain, weakness, or any mention of not wanting to live — escalating immediately per policy if they appear. Her actions do not treat the anorexia; they keep the person safe and open a door to care.
Key takeaways
- Defining triad: restriction → significantly low weight; intense fear of weight gain; disturbed body experience.
- The disorder is usually ego-syntonic — restriction feels purposeful, so denial is a symptom, not lying.
- Report immediately per policy: chest pain, palpitations, fainting, severe weakness, thoughts of self-harm or suicide.
- Refeeding is provider-directed and medically supervised (refeeding syndrome risk); nurses monitor and report, never manage feeding alone.
- Amenorrhea is no longer required for diagnosis (removed from DSM-5) — a classic exam trap.
- The binge-eating/purging subtype still requires significantly low weight — the main difference from bulimia nervosa.
- No single cause: genetics, temperament, culture, and environment interact; family-blaming theories are historical.
- Person-first language: say "a person with anorexia nervosa," not "anorexic."
Check yourself
5 review questions from the chapter. Try each one, then open the answer.
What are the three defining features of anorexia nervosa?
Show answer
Restriction leading to significantly low body weight; intense fear of gaining weight or behavior that interferes with weight gain; and disturbed body experience, including lack of recognition of the seriousness of the low weight.
Why might a person with anorexia nervosa resist treatment or minimize their symptoms?
Show answer
Because the disorder is often ego-syntonic — the restriction feels like control, success, or identity — so denial and minimization are symptoms of the illness, not dishonesty.
A patient with anorexia reports chest pain and palpitations. What should the nurse do?
Show answer
Report immediately to the provider and follow facility policy; cardiac symptoms and electrolyte disturbances can be life-threatening. The nurse does not manage the emergency alone.
What is the main difference between the restricting subtype and the binge-eating/purging subtype?
Show answer
Both require significantly low weight; the binge-eating/purging subtype adds regular binge-eating or purging behaviors, bringing additional electrolyte and cardiac risks.
Why is refeeding after prolonged starvation medically supervised, and what is the nurse's role?
Show answer
Because restarting nutrition after starvation can trigger refeeding syndrome — severe electrolyte shifts that can cause dangerous heart rhythms. Nurses monitor for warning signs and report promptly; feeding regimens are directed by providers, never by nurses on their own.
Study tools & related lessonsKey vocabulary · Related
Key vocabulary
- Anorexia nervosa
- Eating disorder of energy restriction, fear of weight gain, and disturbed body experience
- Ego-syntonic
- Illness features that feel consistent with the person's sense of self
- Refeeding syndrome
- Dangerous electrolyte shifts when nutrition resumes after starvation
- Lanugo
- Fine downy body hair that develops in starvation to conserve heat
- Amenorrhea
- Absence of menstruation
- Blind weight
- Facility practice of weighing a person with their back to the scale
Sources & references
This lesson was adapted from the open educational references above; their licenses and attributions are preserved. See Copyright & Licensing.
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