Water is meant to help you digest your food better, to keep your cells, tissues, and organs functioning properly, to keep you hydrated, and to fill your stomach up. When you are losing weight, your metabolism will increase, and the drinking water will affect that--for the better.
We are supposed to eat about every 4 hours and get in about 8 glasses (64 oz) of water a day; oftentimes, we mistake thirst for hunger. It is recommended to wait 15-20 minutes after drinking a glass of water and see if hunger goes way. If it does then you'll know that you were really thirsty.