Eating Right is very important

I have come accross this frend who recommends drinking 3 liters of water, drinking lime water, green tea and eating less to stay fit and healthy. I m gonna try to follow it to the core and let's see if i can adapt to it. But having an ideal weight and maintaining it is a very important issue which most of my friends are facing.Now lets see how much weight i can maintain and i hope for the best