Red Panda,
I won't pretend to understand what is going on with your body....but I would like to share some thoughts and ask some questions.
First-off....we have to ask ourselves a fundamental question: if 2 people with absolutely identical life-styles, height, size, age, etc...both eat 3,500 calories, do you think one's body may store fat while the other just doesn't? Under conventional theory (calories in vs. calories out)...it would seem that in the end it's really about how much is eaten.
After getting your first injection, did you begin having more hunger and eating more?...or did you continue eating the same amount and just suddenly started inflating? What exactly changed?? I'd really like to know if your calories remained static or if you began eating more? Was it a hormonal change the altered your hunger and made you eat more, or do you think your body just started metabolizing things differently?
I can't imagine the injection could permanently alter your body....so I'm sure it's just a matter of time until things return to normal. Also, as we age many people say their bodies switch gear and change....could the injections have coincided with a bodily change and you're just figuring it's injection-related?
The one thing I do know is that, in the end...it is what it is and you'll just have to deal with it from here. Eat right, exercise and work your way back. Many people are born with bodies that have a permanent programming for what the injections turned you into. My point is, it can be done and you'll just have to get on it and make it happen.
As for the question....the body pretty much has an equillibrium when it comes to hydration. Sure, the injection could have pushed things one way or another, but I'm pretty sure such a big increase in sizes could not entirely be comprised of purely water....under the skin is not bags of water, it's fat....and that fat got there when food was converted into glucose and needed to be stored. What I'm saying is that you still had to eat your way there. Perhaps in the past you could eat a lot and your body just didnt' seem to store it...but there's no way you could eat low-calories and still keep stacking on the fat: each pound of fat originated as food going into your mouth....you just can't get away from that. The hormones could tweek your hydration, hunger and metabolism....but in the end you still must have consumed more calories then your body needed. What do you think?