Use
Protein helps repair and build muscle tissue. Normally, the protein from the food you eat performs this function sufficiently, but people who are trying to build muscle work out harder than the average person, so they cause more muscle damage. This necessitates additional repair, which requires additional protein. Your body also needs a small daily caloric surplus to provide the raw materials that build new muscle tissue, and protein supplements can provide both protein and calories in a single, compact dose.
Protein Source
All protein is good protein, but the most effective supplements come from complete protein sources such as whey, casein and soy. These proteins contain all of the essential amino acids, while plant proteins like hemp and rice contain only a few. Relying only on a single incomplete protein leaves you at risk for a deficiency in whatever amino acids that source doesn't contain, and your muscle repair and growth may be hindered. Fast-digesting proteins like whey and soy are useful for pre-workout fuel, workout recovery and between-meal snacks because they leave your stomach and enter your bloodstream quickly. Slow-digesting proteins like casein provide more of a slow-release effect, keeping protein levels stable for a longer period of time. This makes them more effective as meal replacements.
Amount
Even bodybuilders don't need as much protein as many of them think. According to the American Dietetic Association, 0.77 g per pound of body weight is sufficient -- that translates to 154 g per day for a 200-lb person. Protein content varies widely by brand, but the average is about 30 g of protein per serving. Keep track of your diet for a few days to get an idea of how much protein you get from whole food sources, and choose a protein supplement that fits in with your habits. It's not a case of "more is better" -- consuming too much protein can cause liver and kidney damage over time, and it won't help you build muscle any faster.
Creatine
Creatine is an amino acid that may increase the energy source within the muscle, leading to improved performance during anaerobic activities like weight lifting. The evidence is far from conclusive, but some research has shown that creatine supplements can help increase muscle mass and strength -- but some people are non-responders. According to the University of Maryland Medical Center, younger people benefit more than older people, and people with naturally low creatine levels -- like vegetarians -- may respond better than someone with high creatine levels. Many protein shakes include creatine, or you can use a separate creatine supplement. Creatine generally entails a loading dose of 5 g four times per day for a week, followed by a maintenance dose of 2 to 5 g per day. The creatine in your protein shake remains at a constant level, which precludes a loading dose -- but that just means it may take longer to take effect.
