I've seen my mate/workout partner, who's 5'8 190 in single digits body fat, go without meat for weeks at a time, guys benching into the 400's and can DL 500+... Not intermittent fasting but it shows you do not need a ridiculous amount of protein.....
I don't try IM fasting myself because there are some days I need to take in a real shitload of calories so trying to do that in an 8hr window just doesn't seem practical in my case, I've noticed a lot of people seem to swear by it though...