The blood they drink is used up... like calories I assume. Unlike peeing which takes out all the unnecessary toxins out of the body... blood.. is used up entirely for the body. So they dont need to pee.
Now my question is.. when they had to pretent to eat and drink in front of public... where does the water or food go afterwards?
i do not think they puke or go to the restroom i dont think that there body is made for it