Hahaha! Tae Bo being "90s!"
You can do whatever gets you through the fast. The standard is water and tea but I think some people will go up to 50 calories. I do lemon and water usually - sometimes tea. It's also perfectly ok to start with a shorter fast - 16 hours or so (from 8 pm to noon).
I know there are some people who experience digestive "issues" but I've never had anything weird happen. I mean, I think as long as you're still eating healthy and not consuming enough fat to make you ... you know... you'll be fine.