Well done, Sarah. Glad you're loving bodyrock and morning workouts. I'm not even sure what it is. When I started lifting heavy again, it took my body about 6 weeks (and, ironically, that's what I later read online) before it understood what was happening. This has to do with muscles retaining water and is a temporary water gain! Over time, your muscles adapt and your weight drops back down to normal. That's what I've read and what I experienced anyway.