The Science of Fasting

I have a friend of mine who lost 100lbs and kicked diabetes fasting. guy was over 300lbs at one point and took control of his life. His doctor and his friends got worried about him because he got skinny so quick. He did become a little preachy about sugar.
understandable because of the lifestyle change. Kinda like if you quit smoking crack you're most likely to tell people " yeah that crack is bad for you." lol.