All body functions require water, including fat consumption. You can drink too much water (Hyponutrimia) is bad, but not easy to accomplish. Just make sure your pee is always clear unless your vitamins color it. If you are thirsty, you are already dehydrated.
NO, hydration has nothing to do (or very liitle) with being overweight.
The more water you drink, the less you will retain, actually. When you get dehydrated, your body tries to hold on to as much water as it can (so it does not die). So, drink as much as you can and the body will expect that it will always have it available, and get rid of the stores (bloating, puffiness).
