Cachexia (/kəˈkɛksiə/[1]) is a syndrome that happens when people have certain illnesses, causing muscle loss that cannot be fully reversed with improved nutrition.[2] It is most common in diseases like cancer, congestive heart failure, chronic obstructive pulmonary disease, chronic kidney disease, and AIDS.[3][4] These conditions change how the body handles inflammation, metabolism, and brain signaling, leading to muscle loss and other harmful changes to body composition over time.[5] Unlike weight loss from not eating enough, cachexia mainly effects muscle and can happen with or without fat loss.[6] Diagnosis of cachexia is difficult because there are no clear guidelines, and its occurrence varies from one affected person to the next.[7]
Like malnutrition, cachexia can lead to worse health outcomes and lower quality of life.[8][9][10]