We all know that the only way to build muscle is to use the muscle. This can be done through exercise or some other form of vigorous activity. More specifically, when using the muscle under high intensity, you are breaking down muscle proteins that will later be built back up stronger. The balance of these two processes, protein breakdown and protein synthesis, is referred to as homeostasis.
Muscle homeostasis occurs without exercise all the time to maintain proper muscle utilization and health. Exercise, on the other hand, challenges this balance and, depending on what you do, can stimulate muscle hypertrophy or muscle breakdown.
The biggest external factor manipulating the process of protein breakdown is exercise. If "Protein Breakdown" outweighs "Protein Synthesis" then you will lose some muscle. Although your body will synthesize protein for the next 24-48 hrs after exercise, "Protein Synthesis" will maintain or lose to its counterpart "Protein Breakdown" without any external factors to help out. Conversely, if "Protein Synthesis" outweighs "Protein Breakdown" then we will build muscle.
Alternatively, protein powders and supplements can also feed your muscle hunger. New studies have even shown that Chocolate Milk can be one of the best post workout drinks available. The carbohydrate and protein combination in chocolate milk is exactly what your broken down muscles need to initiate proper synthesis of new muscle.
The limiting factor to this SeeSaw diagram is that you MUST have muscle breakdown before having muscle growth. So now, in order to build muscle, the diagram has a progression that looks like this:
Exercise causes breakdown, which then initiates synthesis. But, the next step in the progression is dependent on the protein available. Therefore, we have to consume enough dietary protein to outweigh the amount of breakdown and cause muscle growth. So eat up and beef up!