I have struggled with acne all my life and fasting does clear it up but you have to follow a plant based diet low in fats to keep your skin clear afterwards. Dairy products and meats really cause breakouts on me. And avoid processed foods too.
I think I may have a hyperthyroid problem too. i had one doctor who thought I might but I never followed up on it. I am fasting too, hopefully fasting will get rid of my thyroid problem as well.
Good luck to you.