My first day in I lost seven pounds. I nearly fell off the scale with shock. Most of it, if not all was water, but once all of the excess retention was gone the fat started flying off at an incredible rate as well. Beware of the hated plateau though, it comes out of no where and takes a lot of discipline to not freak out over it. Not trying to scare or discourage you, just want to prepare you for the phases this WOL leads you through.