2-3 day water faaast? help :$?

kkk so ive been on the skinnygirl diet nowww for about 23 dayss. ive lost 15 lbs soo faaar! 2 days ago ii did a 3 day diiet, fast, day 1, only fruits day 2, only veggies day 3. today i was on the veggies only when i cheaated, ii had a GIANT choco chip cookie, pizza, a chunk of peanut butter choco fudge and a buurger. ill prob gain weiight after that soo starting tomorrow i want to do a 3 day water fast. can you guys tell me if imm going to faint or something during this? and have any off you done thisss then DID NOOOT gain back the weight you lost. after the 3 day diet i plan too go to very low calss starting at 300 then everyday adding 50 cals till im back to normal cals of 1200. can youu plese help me without lecturing me about how its not good for my body? thaaanks :)