Hi Daven and thanks for reading
The effects of a water fast will be familiar to you, just more prolonged. If you've ever gone past your lunch time by a few hours, you know what it's like: first you feel incredibly hungry, you become hyper, and then that slowly turns into hunger disappearing and being replaced by being a tad dizzy, and having a headache. You can expect the same symptoms from a water fast, until they finally settle and you find your equilibrium again.
HOWEVER, be incredibly careful. There is a fine line between what's normal and dangerous which is why your question is great. To add to the above, everyone knows themselves and what feels like "being normal." Personally, I'm an extremist and gone past the boundaries many times, which is why I absolutely emphasize the importance of being incredibly careful, specially if you've never done it before.
If anything doesn't feel right, or you start wondering if you should stop, by all means, stop. You can always recover and pick up where you left later. And start accumulating immunity to it. Hope this answer, in some way, your question, and helps. Thanks