Replacing coke with water will help you lose weight because you are reducing unnecessary calories. Water is, of course, wonderful for all parts of our body anyway
I agree, it's easy to confuse hunger with thirst if we don't actually feel thirsty, but all we need is a little water. Many vegetables and fruits have a high water content, so eating them helps. Sometimes I'll find myself standing in front of my fridge (and wondering how I got there

) and I try to ask myself if I'm really hungry or will a glass of water suffice. Most of the time, water works. I had to force myself to do that a few times before it started to come naturally. Sometimes, though, you really are craving nutrition, and veggies are the wisest way to go.