Whatever you do, do NOT drink diet coke. Or any other diet soda with Aspartame in it. Ever - not just on the fast. Do a search for Aspartame and see all the problems associated with it. I am telling you this from personal experience. I have been told (and I believe) that it's better to eat pure Sugar than use that sweetener. Also, if you are fasting to lose weight, it's been documented that diet soda will actually trigger your hunger and cause you to stop losing weight.