I Water Fast several times a month, no schedule, just when I think I have 3-5 days of quiet I go for it. It may not be a "true" Water Fast because I have to keep up my antimicrobial herbs and some vitamins, but I always feel better, and it helps to get this water weight I have accumulated while being sick for several years.
Sometimes I am stunned when the scales goes up a couple of lbs, but it always goes back down, and I maintain the loss.
I also started using a FIR (Far-Infrared-Sauna) sauna, and it helps also. It helps pull toxins out of your skin, and improves the appearance.
I saw you asked about skin on another post, I credit Vitamin C for keeping my skin tight. It has had no ill effect on my water fast.