Protein supports tissue growth and recovery of damaged muscle tissue. When you lift weights, you tear down your muscles fibers. It is in the recovery process that you become bigger & stronger, not during the actual workout – that is if you pay attention to nutrition, especially your protein intake. Research tells us that you need 1.8g of protein/kilo of lean body mass. You need to strive to eat 14-30 grams of protein every 2-4 hours and this should be spread throughout the day in 4-6 meals. This will ensure better absorption rates. If the protein in the diet is of poor quality (missing 1+ amino acids), the body will not be able to build the proteins it needs for all of the varied roles that involve protein. If these amino acids are not obtained from the diet, the body is forced to obtain them from other proteins, particularly muscle tissue.
Popular high protein diets are not the answer for weight loss or athletic performance. We can store carbohydrates and fats, but we cannot store protein. The nitrogen in the amino acids is toxic and must be excreted continuously. If a person consumes too much protein beyond what the body needs, the remaining is converted to fat and stored as such.