I do keto once a year for about 3 months, and truth be told I feel like a superman. I feel more energetic, loose a ton of fat (ironically with increased fat intake), get more stuff done and overall feel better. The only reason is stop doing it is because I'm a sucker for sweets :)

I started all this by asking a friend of mine who's a personal trainer what's the best way of loosing 15 kilos (because I was fat) and he prescribed me a keto diet. Lost all 15 in three months and no, haven't gotten them back.

EDIT: on the flip side, my wife's menstrual cycles got completely messed up and her periods started to hurt a whole lot more, so she stopped it.