Muscles are made up of mostly proteins, in turn protein is used to build and repair cells.
If the body does not absorb it, protein can be converted into energy at the rate of four calories per gram of protein. By taking in more protein than your body can use, you are taking the chance of some of the resulting calories being stored as fat. It will be a couple of percent off but it will give you a basic idea of where you are currently. There are studies that show that 1 gram per pound of body weight is excessive but when it comes to protein it is better to have too much than too little. A blend of proteins is definitely the way to go.