Drinking a lot of water isn't going to make you lose water weight as far as I know. Cutting down on carbs however will. And yes, it is sort of noticeable, especially your face will look skinnier and less bloated.
sorry..but this is a very stupid idea, your body needs water, you can't torture yourself so that the other people like you. to hell these others..accept me as i am or leave and close the door.
not as much as if you lost the body fat instead, but don't drop below 20% without a Doctor's check...