Actually, I don't think diet coke is allowed in the first two weeks. I am in Phase II currently but, I remember Phase I is only supposed to be water, tea, or coffee(preferably caffeine free).
I've been on this diet for a little over 7 weeks and lost 15lbs!!! My friend read a write up on this diet in a popular health and fitness mag that said the first two weeks aren't the healthiest but, after that (Phase II and III) is just good healthy eating!!
Keep it up! The lbs just fall off!!

Actually, I have to make myself eat certain things that are now allowed in Phase II because I just didn't crave them any more!!