Cachexia (pronounced kuh-KEK-see-uh) is not simply eating too little. It is driven by systemic inflammation and tumour or disease-derived metabolic signals that actively break down muscle and fat — even when nutritional intake appears adequate. This makes it fundamentally different from sarcopenia (age-related muscle loss) or simple starvation.
Diagnostic criteria generally include greater than 5% involuntary weight loss in 12 months (or BMI below 20 kg/m²) combined with reduced muscle strength and elevated inflammatory markers. It is most common in late-stage cancer — particularly lung, pancreatic, and gastrointestinal cancers — but also in advanced heart failure, COPD, and end-stage renal disease.
Nutrition’s role is important but limited. Adequate energy and protein intake can slow the rate of loss and support treatment tolerance (for example, maintaining weight during chemotherapy improves the ability to complete a full course). However, nutritional support alone cannot fully reverse cachexia because the underlying metabolic driver — systemic inflammation — persists while the disease is active.
This is a critical distinction: families and patients should understand that cachexia-related weight loss is not a failure of appetite or willpower, and cannot be corrected simply by “eating more.” Aggressive forced feeding can cause harm and distress without reversing the process.
Management is multidisciplinary: clinician, oncologist or specialist, registered dietitian, physiotherapist. Goals should be individualised and realistic — often focused on comfort, quality of life, and tolerating treatment rather than weight gain.