The longest i've been able to fast is 4-5 days. It's definitely an experience! I think it's best to work your way up. I first started with a 2-3 day fast... My goal for now is a 10 day fast and from there I'll see if I can continue. The real hunger pains are over for about the first 2 days normally and then your body kicks into this extended fasting mode. The mind becomes very clear and you begin to see the world differently... especially when fasting as part of a religious experience... there's basically two kinds of fasting... fasting for health and meditative/religious fasting... or of course both can be accomplished... generally, fasting for health still includes comsumption of juiced fruits/vegetables and sometimes supplements... On the other hand you have those that only choose to drink water and still, some others choose to not comsume even water... which can be dangerous but you have to know what you're doing.