How much weight could I lose by drinking just water, and eating less than 500 calories a day?

I was on yahoo answers just looking at random questions. Some girl said she lost 15 pounds in a week by only drinking water. First it depends on how much you weigh. The more you weigh, the more you can lose. Secondly, it's really risky. Something that happens to a lot of people, and me as well, is that you cut out your favorite foods (bread, pasta, etc). It's easy the first week or so but then you'll start to crave it and most end up binging making you gain back all the weight you previously lost. Just keep doing what you're doing, eat healthier, only when you're hungry, and don't eat after 7P.M.