I went on a 10 day water fast, by day 6 I was fine through the first 5 days of fasting. I didn't even have any sort of induction period. On day 6 I was suffering from confusion and a weird mental state at work. I took a break and decided to break my fast with soda. My confusion and delirium went away, but I still didn't feel too great. I had another episode like this two days later. I originally thought it was hyponatremia so I started drinking pedialyte, I felt better after a while.
I had to go back to eating. It took me at least 3 weeks to get my speed back at work and to not feel like crap all of the time.
Now I experience hypoglycemic symptoms if I don't eat after a few hours. I have had to eat in order to cure my shakiness twice these past few weeks.
I never had any of these problems before I went on a waterfast, now I do.