I have done a 21 day Water Fast before and thought it was great. I only had hunger headaches the first day. The first week I didn't notice much because body is shutting down. Second week was euphoric, mental clarity, all senses enhanced. Third week I noticed major physical changes. They say it takes 21 days to make a habit and 21 days to break a habit, well after the 21 days I retrained my body to eat specifically the way I wanted. That was three yrs ago. I am now on day 10 of my fast and I am going to see how long I can go this time, I remember the last fast, on the 21st day I still wasn't hungry and probably couldve gone longer but three of us did it together so the others wanted to eat. This time I am doing it by myself so I am going to go as long as I can, 30 for sure but hopefully 40 days, I have the mass to support it. And for all those that think it is dangerous, its really not if you have the mass to lose.