Quoth Cheesegear:

It doesn't need to eat, drink or sleep. But weirdly it can still drown or suffocate - I'm sure we can figure out a way for that to make sense.
Hey, it works for Murderbot. Although it makes even less sense there, since it's science fiction: What does the oxygen it breathes react with, if it doesn't eat? But it's a good enough series that it's easy enough to sweep under the rug.

In a magical setting, it's even easier.