From my observation the bigger u are the more weight people usually lose. For example a person 5'5 at 250 may lose weight faster vs then 5"11 200pds. Anyway, from my experience you just have to take it day by day. If you cant complete it the first try start again . I always say to just build up from 3 to maybe 7 and beyond. Also, the refeeding stage is maybe justjust as crucial as the fast itself. You really cant control how much you will lose it ...u may lose 20 or more maybe less only time will tell. Of course many people do things like exercise and enema to speed things up but I like a natural approach and to just let my body rest as it heals itself.