Water weight?

[Tarclis]

"They" say the beginning of your weightloss is water weight, and therefore comes off easier and faster. How MUCH of my weight is water weight? At what point can I expect my weight loss to slow down, when I'll be losing fat?

Info that might help;
Start: April 6
192 lbs
Eating loads of garbage, never moving unnecessarily, and no water ever

Now: May 2
176.4 lbs
Counting calories, eating healthier foods, 10+ cups of water daily, and just barely starting to get into the habit of exercise  

[Testicular Diabeetus]

Really it varies from body to body.
They say that you only want to lose 2 -3 pounds a week, I guess when you start losing 2-3 pounds a week, that will be fat loss.
I'm no doctor though this is just what I think.
I could be wrong.