I am not trying to be negative in any way but you do seem to be in the wrong forum as a true Water Fast is mostly concerned about detox, becoming more self aware (spiritual enlightenment for many) and resting your body. All the questions you ask can be answered with a simple Google search or doing research before you start . No, nothing, at all should go into your mouth while Water Fasting but pure, clean water. Period. If you take in a measly 100g protien bar your body falls out of ketosis and into starvation mode which will In turn go toean muscle mass first. See why playing with a bite here and a nibble there does more harm than good? The purpose of Water Fasting is to stay in ketosis to burn faulty cells, fat cells and detox. If you are overly concerned about a small amount of muscle mass lost you definitely should go to the body builders forum as they have there own methods of getting lean. The main goal of Water Fasting is not for weight loss. Good luck with what you decide to do.