Waterfasting with supplements.

Im new to Water Fasting and i have some questions. During Water Fasting i want to take supplements, overall about 15 capsules. If i take that will i have to do the refeeding process. I want to take the supplements for the added effect of taking them on a empty stomach. Also i want to work out, so is it possible to build muscle, and could i still run a little bit like 2 miles. And i've read that you gain weight afterwards and that it kills your metabolism. If that is true should i not do a Water Fast since i want to build muscle afterwards.