Previously the commonly accepted wisdom on the subject was that drinking water fills your stomach and leads to people consuming fewer calories over all. In this study the participants were already given reduced portions and the water drinkers still outpaced those who didn’t drink extra water.
I can attest to the benefits of drinking more water! I’ve recently lost quite a bit of weight, and when I would notice that my loss would slow or even stop, it would almost always coincide with a decreasing in my water intake. I’d kick up the water drinking, and weight loss would start again.