General pathology · Nutritional pathology
Cachexia, anorexia nervosa and bulimia !
- Topic
Cachexia is inflammatory wasting that eating alone does not reverse; anorexia and bulimia are eating disorders with serious body effects.
Updated 2026-11-01
What it is
Cachexia accompanies cancer, heart failure, COPD, chronic kidney disease and HIV: cytokines break down muscle and fat even when the patient eats. Anorexia nervosa is self-imposed starvation with endocrine, bone and heart consequences; bulimia nervosa combines binge eating with purging, whose main dangers are electrolyte disturbances and injury to the upper digestive tract.
Step by step
- Tumour or chronic disease activates macrophages and lymphocytes.
- TNF, IL-6 and IL-1 act on the hypothalamus (less appetite) and on muscle and fat.
- The ubiquitin–proteasome system breaks down muscle proteins; lipolysis empties fat cells.
- The liver switches to acute phase proteins; albumin falls.
- Weakness, fatigue and poor treatment tolerance follow, and survival falls.
Three forms of weight-related disease
| Condition | Core mechanism | Typical findings |
|---|---|---|
| Cachexia | Cytokines (TNF, IL-6, IL-1) and tumour factors increase muscle breakdown | Muscle and fat loss not reversed by feeding, weakness, anaemia |
| Anorexia nervosa | Restriction leads to a starvation state and low GnRH | Amenorrhoea, osteoporosis, bradycardia, hypotension, lanugo, low T3 |
| Bulimia nervosa | Binge eating with vomiting, laxatives or diuretics | Often normal weight, hypokalaemic metabolic alkalosis, parotid swelling, enamel erosion, knuckle calluses |
Clinical notes
- In anorexia nervosa, low oestrogen and high cortisol cause bone loss that may not fully recover.
- Repeated vomiting can tear the oesophageal mucosa (Mallory-Weiss) or rupture the oesophagus.
- Refeeding a severely underweight patient carries the risk of low phosphate, potassium and magnesium.
Test yourself
Think of the answer, then tap the question to see it.
Why does extra feeding not reverse cancer cachexia?
The wasting is driven by cytokines and tumour factors that keep muscle breakdown and lipolysis active, not only by low intake.
Which acid–base disorder is typical of repeated self-induced vomiting?
Hypokalaemic, hypochloraemic metabolic alkalosis from loss of gastric acid and volume.
Why do women with anorexia nervosa stop menstruating?
Starvation suppresses hypothalamic GnRH, so LH, FSH and oestrogen fall.
What is Russell sign?
Calluses or scars on the knuckles from repeatedly using the hand to induce vomiting.
Related
- Local effects of tumours and cancer cachexia
- Atrophy
- Severe acute malnutrition: marasmus and kwashiorkor
- Systemic effects of inflammation: fever, acute-phase proteins, leukocytosis, sepsis
Related conditions
- Anorexia nervosa
- Bulimia nervosa
- Binge-eating disorder
- Refeeding syndrome
- Hypokalaemia
- Metabolic alkalosis
- Osteoporosis
- Functional hypothalamic amenorrhoea
- Mallory-Weiss syndrome
- Oesophageal perforation (Boerhaave syndrome)
- Sarcopenia
- Heart failure
Elsewhere in DurgiPedia
- Ubiquitin–proteasome system
- TNF-α
- Interleukin-6
- Prolonged fasting and starvation
- Appetite hormones: leptin, ghrelin and incretins
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Nutrition in Cancer Care (PDQ®)–Health Professional Version (National Cancer Institute, 2026); Anorexia: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2026); Bulimia: MedlinePlus Medical Encyclopedia (MedlinePlus, US National Library of Medicine, 2026).
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Representative model, for educational purposes only.