actually atkins would keep your gallbladder empty with the fat intake.
the high fat though is only for the first two weeks. basically it is about eating closest to nature in the end. i am sick of it getting a bad rap for its induction phase. if you dont do it right you will be sick.
anyway....
how to not gain weight after a fast. after two days your metabolism will slow down if you are fasting. you will have a slow metabolism for at least a month post fast.
also if you eat processed and crappy foods you will get fat. no matter what. fasting or not.