I just did a five day fast. Nothing but water.
I had an unexpected outcome:
I’m 65 and have grown accustomed to getting up three or four times a night to go to the bathroom. I finished the fast Monday. I’ve slept through the night every night since.
I didn’t see that coming.
Those let me sleep through the night without bathroom visits. It took about a month to get to no visits, but it worked for me.