What do you drink - just water? Any supplements?
Yes. pretty much just water, black coffee, tea. Water with minerals added is acceptable to maintain electrolyte balance.
There are variations available depending on your goals that allow for what are known as once a day ‘fat bombs.’
Monitor both blood glucose and ketone levels to be sure you stay at safe levels.
https://drmindypelz.com/a-beginners-guide-to-fasting/
Ketogenic electrolyte powder mixed with water.
Make sure you get the unflavored kind...no artificial anything.
You can’t take supplements other than some extra potassium...your stomach will reject them.
I did 96 hour fast twice a month rather than chemo after a tumor was removed. Cancer free for 3 and a half years.