Each week, Verywell explains a term from health, medicine, science, or technology.
How to say it: Cachexia (ka-SHEX-ee-ya)
What it means: Wasting and malnourishment related to a disease.
Where it comes from: Greek, kachexía, meaning "poor state"
Where you might see or hear it: If you are diagnosed with a serious illness like cancer, your body might need to start burning a lot more energy. Sometimes, your body uses up so much energy that you become underweight and not nourished enough. If this happens, your provider might explain that it's called cachexia.
The condition usually happens in people with cancer or diseases like HIV/AIDS. It's a little different from being malnourished from starvation. You can have cachexia even if you're eating—your body just needs so much energy that you may not be able to keep up. With cachexia, you're also losing muscle, not just fat.
When you might want to use it: If your loved ones are worried that you look "gaunt" and thin from your illness, they may try to get you to eat more. Even if you want to eat, it might be challenging if you are very sick.
It will help to tell your loved ones that cachexia is different from not eating enough. The disease that you have is putting so much demand on your body that the energy you get from food is being used up very fast.