I do actually, did it twice this year one week in January and then again during lockdown during the last week of March I think. I heard about it from the guy who came up with it, he wrote a book about the merits of a Mediterranean plant-based diet (with the occasional fish, but no meat) that resonated quite well with me, since it's easy to implement and also really delicious - I mean there isn't really all that much that go wrong with eating vegetables, some bread and pasta, nuts, olive oil, and fish (also had the welcome side-effect to reduce my meat-consumption to pretty much zero now)

Anyway, so after I switched my diet I decided to give his FMD a go and was pleasantly surprised - it's pretty tough, the second and third day were the worst for me, I was just incredibly hungry (and honestly speaking I did'n really achieve any mental clarity during those days), just went on a ton of walks. But I felt I gained a lot of mental strength following that experience, it was easier for me change eating or drinking habits simply because this exercise of control over your most basic need really provides you with a boost of confidence.

You obviously also lose a lot of weight (around 4kg per week) and I've lost even more since then, maybe 20kg since the beginning of the year (though that's a combination of sport, this pescatarian Mediterranean diet, but probably also those 2 fasting sessions). I plan on doing it again, though I want to try out 'real' water fasting next time. I think this is a great starting-point into fasting, though.