Although the "volumizing" effect of creatine is one of the benefits. I think too many people are taking it for the wrong reason (weight gain) and is why they "think" it doesn't work. And why when people cycle off of it they say the "lost everything" and look at is as a bogus supplement.
Creatine is an essential player in one of the three primary energy systems used for muscle contraction. It exists in two different forms within the muscle fiber: as free (chemically-unbound) creatine and as creatine phosphate. This latter form of creatine makes up two-thirds of the total creatine supply. When your muscles contract, the initial fuel for this movement is a compound called ATP (adenosine triphosphate). ATP provides its energy by releasing one of its phosphate molecules. It then becomes a different compound called ADP (adenosine diphosphate). Unfortunately, there is only enough ATP to provide energy for about ten seconds, so for this energy system to continue, more ATP must be produced. Creatine phosphate comes to the rescue by giving up its phosphate molecule to ADP, recreating ATP. This ATP can then be "burned" again as fuel for more muscle contraction.
The bottom line is that your ability to regenerate ATP depends on your supply of creatine. The more creatine you have in your muscles, the more ATP you can remake. This allows you to train your muscles to their maximum potential. It's that simple. This greater ATP resynthesis also keeps your body from relying on another energy system called glycolysis, which has lactic acid as a byproduct. This lactic acid creates the burning sensation you feel during intense exercise. If the amount of acid becomes too great, muscle movement stops. But if you keep on regenerating ATP because of all the Creatine you have, you can minimize the amount of lactic acid produced and actually exercise longer and harder. This helps you gain strength, power and muscle size; and you won't get fatigued as easily.
Creatine has also been shown to enhance your body's ability to make proteins within the muscle fibers. Two of these proteins, actin and myosin, are essential to all muscle contraction. So when you build up your supply of these contractile proteins, you actually increase your muscle's ability to perform physical work.
