Need to loose weight for basketball?

My coach says i need to get in shape he didnt say loodse weight but i want to for my health does anybody have any good diets or diet plans or should i ask my doctor to subscribe me a diet? But since i playball i want to loose my stomach to be able to jump and dunk the ball i just slap the back bored and im tied of that i want to dunk. Can somebody help me please