You already read chrisb1's message, who had a very good advice for the original poster.
I agree with chrisb1 that post fast plant based diet will help you a lot. It takes a lot of work to and time to get the skin to totally smooth out.
Your body will use fat and other junk first. Then it will slowly work on the skin.
Also do not worry about losing muscle, unless if you do partial eating and go beyond 40 days of fasting. No minerals are required on a water only fast. Nothing but water should be taken, no teeth brushing, gum chewing or supplements of any kind.
Please post your experience here so others can learn from your experience.