If it's anything like the 18 in 4, I'd get that idea out of your head.
I believe the diet is made up of small portions of fruits and vegetables with some chicken and beef randomly thrown in there. It's not something that someone would be able to keep up for more than a short term diet, and we all know what happens when you go off the crazy diets.
But seriously, 18 lbs in 4 days? I didn't even lose that much when I was not eating ANYTHING, and I was 270 lbs at the time! (When I got my tonsils out, I couldn't even drink water).