I did the HCG Diet at the beginning of this year and lost about 38 lbs. in a 23 day round.
There are a lot of versions of it floating around, Make sure you follow the original Simeon's Protocol.
I've considered doing another round of it to lose the last amount of fat around the midsection, but afraid of the low calories and possible muscle loss.
I'm also very interested to hear opinions from a bodybuilding perspective on whether or not the HCG truly protects one from muscle catabolism.