I've done this cleanse so many times over the years from 3 days to 45.
I don't care what anyone says. Every friggen time I've lost muscle. I'm sure normal or average people don't notice but anyone who lifts weights has to. And I mean 50lbs+ in weights not 2lb dumbells. So yeah, plan on doing it and getting my 100+ grams of protein in via supplements.
Anyone else ever do this? Not looking to be talked out of it. I'm just curious really and ranting. I did this a few months ago for 2 weeks straight and my strength went down and I lost size and it took me a bit longer than I liked to get back what I lost. I also lost some fat with it which is great but it's the muscle I wanted to keep.