That's the whole point. But here's the good part: you can, and should drink anything that's non-caloric. This includes:
- Unsweetened black coffee
You get the idea: as long as it has 0 calories, you can drink it. This also includes artificially sweetened drinks like Vitamin Zero water etc that contain electrolytes. I don't really like artificial sweeteners though since they have their own downsides, including interfering with fat loss (aspartame), but they're not a deal breaker.
Caffeine also serves as a mild appetite suppressant. It is common to feel hunger pangs, but this happens since you're in a habit of eating every few hours. As your body adapts to your fasting lifestyle, they only get easier to get through, and the best way out is to focus on something else and keep yourself busy.
For longer fasts (36 hours or more), people have reported drinking bone broth / vegetable broth — which may help you get settled into the routine without completely destroying the fast. Again, use it only as a crutch to get there if you need to.