How much weight you loose during a fast depends on your metabolism too. On average people loose about 2 lbs a day in the first week of a Water Fast (This information is form Shelton's Natural Hygiene I believe). But again it is mostly water. As I said I fasted in summer. In hot weather your metabolism is increased and you sweat more. I never went beyond the 6 days, but people say you don't loose weight as quickly in the following days or weeks. I still believe that exercise and a healthy Diet are the best way to stay thin if you are consistent.