Personally, I tend to retain fluid easily. Highly sensitive to sodium and preservatives, but I do notice that I retain fluid when I eat alot of carbs. So this week when I began phase II and added a few carbs, I've also added 2 lbs. I'm sure my body is just holding fluid from the carbs so I'm not panicking.
I drink hot water with lemon juice (either fresh or the Minute Maid that you get in the frozen juice section - NOT ReaLeamon Brand because of preservatives) and a little splenda a couple times a day and it helps alot.