Creatine helps make a substance called Adenosine Tri-Phosphate (ATP), ATP provides the energy for muscle contractions. The body produces some of the Creatine it uses and It also comes from protein-rich foods such as meat or fish.

Put simply, the more muscle you have on your body, the harder you can work in the weight room, and the more calories you can burn both during and after your training sessions.
Creatine is a natural compound made in the body and is derived from the diet through meat products. 
In the body, Creatine is changed into a molecule called phosphocreatine which serves as a storage reservoir for regenerating ATP who is the chemical source of energy for muscle contraction and quick energy.