"It's especially important to eat a carb- and protein-rich meal immediately after a workout," Aceto says. "Right after training, it turns out that your body is really lousy at taking carbohydrates and sending them down fat-storing pathways," he says. "So post-training, carbs will be sent down growth-promoting pathways instead." And when these carbs are combined with a protein source, you've got a strong muscle-feeding combination because carbohydrates help deliver the amino acids into muscles by boosting insulin levels. This anabolic hormone drives nutrients into the muscle cells and kick-starts the muscle-growth process.
However, if you increase the demands you are placing on your body by increasing the weight being lifted, lifting the same weight for additional reps, or just doing something that increases the demands that your body needs to meet, then your body will have no other choice but to make the changes and improvements necessary for it to adapt to this environment and remain capable of performing these tasks.
Carducci, C., Birarelli, M., Leuzzi, V., Carducci, C., Battini, R., Cioni, G., and Antonozzi, I. Guanidinoacetate and creatine plus creatinine assessment in physiologic fluids: an effective diagnostic tool for the biochemical diagnosis of arginine:glycine amidinotransferase and guanidinoacetate methyltransferase deficiencies. Clin Chem 2002;48:1772-1778. View abstract.
Sculthorpe et al (2010) has shown that a 5 day (25g/d) loading protocol of creatine supplementation followed by a further 3 days of 5 g/d negatively influence both active ankle dorsiflexion and shoulder abduction and extension range of movement (ROM) in young men. There are two possible theories to explain these effects: 1) Creatine supplementation increases intracellular water content resulting in increased muscle stiffness and resistance to stretch; 2) Neural outflow from the muscle spindles is affected due to an increased volume of the muscle cell. The authors highlight that the active ROM measures were taken immediately after the loading phase and the reduced active ROM may not be seen after several weeks of maintenance phase . Hile et al  observed an increase in compartment pressure in the anterior compartment of the lower leg, which may also have been responsible for a reduced active ROM.
A quantitative, comprehensive scientific summary and view of knowledge up to 2007 on the effects of creatine supplementation in athletes and active people was published in a 100 citation review position paper by the International Society of Sports Nutrition. More recent literature has provided greater insight into the anabolic/performance enhancing mechanisms of creatine supplementation [15,25] suggesting that these effects may be due to satellite cell proliferation, myogenic transcription factors and insulin-like growth factor-1 signalling . Saremi et al  reported a change in myogenic transcription factors when creatine supplementation and resistance training are combined in young healthy males. It was found that serum levels of myostatin, a muscle growth inhibitor, were decreased in the creatine group.
It’s perhaps best known for the aesthetic benefits. Creatine increases muscle size relatively quickly and while that’s in part due to an increase in muscle water content — a good thing, since it means we’re better hydrated — it does indeed appear to lead to actual hypertrophy over time. And bigger muscles aren’t just aesthetic: larger muscles can improve work capacity, explosiveness, fat oxidation, injury resilience, and recovery.
Few supplements have the solid scientific foundation that creatine has. Studies show that it's effective for 80 percent of those who use it. Since creatine is found naturally in meat, the more meat you eat, the less likely you'll need creatine supplementation. Vegetarians or those who rarely eat meat, however, can get huge boosts from most creatine supplements.
As mentioned, protein is essential for building muscle. If you are unable to consume the recommended amount of protein through diet alone, add protein powder for building muscle as a supplement. This applies to nearly anyone hoping to gain muscle mass since it’s not easy to pack in nearly 100 grams of protein a day through chicken, eggs and legumes alone.
In addition to the proper amount of sleep, do not overdo your training regimen. While you might be tempted to think that "more is better," in fact the opposite is true. You can reach a point known as "over-training", in which you'll lose the ability to "pump" (engorge the muscles with oxygen-rich blood) your muscles, and this can even lead to muscle wasting—exactly the opposite of what you are trying to achieve. Here are some symptoms to be aware of if you think you may be falling into the over-training zone:
The harder an exercise is – both in terms of technicality and physical/mental demand – the more rest there should usually be. So exercises like squats and deadlifts should have more rest between sets than exercises like leg extensions and leg curls. And exercises like various bench presses, shoulder presses, rows and pull-ups should have more rest between sets than bicep curls, tricep extensions, chest flies and lateral raises.
Collectively the above investigations indicate that creatine supplementation can be an effective strategy to maintain total creatine pool during a rehabilitation period after injury as well as to attenuate muscle damage induced by a prolonged endurance training session. In addition, it seems that creatine can act as an effective antioxidant agent after more intense resistance training sessions.