Fast mimicking sounds like calorie restriction? Which I know has been extensively studied -- in mice -- and people find it almost impossible to stick to.

I read interviews with a journalist several years ago where they found a small group devoted to it, but the writer was not impressed by their scary "greenish" skin tone and lack of energy. And the whole thing had a serious eating disorder vibe to me.

Anecdotally, Atkins Fast Fasters are pleased with results, and the science -- fat doesn't cause insulin to rise -- is solid still. I think it might work best when people are over their carb flu and more set up to actually burn fat. I don't think it was for Induction, but for stalls.