I've been in ketosis for the last 4 months. (Click here if the word ketosis means nothing to you) 
My reasons: Well not weight loss (although I've toned up - he says modestly), but for decreased inflammation, better digestion, improved skin and sharp thinking, And all that is working quite well. I'm really enjoying it, but it takes a month of feeling a little tired (they call it the Keto Flu) when you first get into it. At least that's what happened to me. Want more details? Check out today's podcast. 
Incidentally, this podcast is with the world's biggest expert in Ketosis - Dom D'Agostino. He's an absolute legend and I'm thrilled to be able to chat to him about so many important aspects of Keto, how to get into it, the benefits and the pitfalls and so on. Thanks Dom!