Protein is necessary for the building and repair of body tissues.
It produces enzymes, hormones, and other substances the body uses.
It regulates body processes, such as water balancing, transporting nutrients, and making muscles contract.
Protein keeps the body healthy by resisting diseases that are common to malnourished people.
Prevents one from becoming easily fatigued by producing stamina and energy.
Protein is found in muscles, bone, hemoglobin, myoglobin, hormones, antibodies, and enzymes, and makes up about 45% of the human body. Muscle is approximately 70% water and only about 20% protein. Therefore, increasing muscle mass requires extra water, extra energy in the form of carbohydrates (to maintain the needs of that extra muscle), and a little extra protein.

According to Dr. Dan Benardot, for an athlete increasing muscle mass at an extraordinarily high rate of 1 kg/week (2.2 lbs of extra muscle per week), only 4 extra ounces of meat per day would be needed. In most surveys that have been done on athletes, protein intake from food far exceeds requirements. The generally accepted athlete requirement for protein is between 1.5 and 2.0 grams per kilogram of body weight. Many studies show that athletes commonly consume well over 3.0 grams per kilogram of body weight. Most athletes need slightly more protein than non athletes. However, muscle strength, size, and shape comes from athletic training, not dietary protein intake

Two to three servings of lean meat or alternatives each day should give enough protein to meet requirements.
Vegetarian athletes may need two to three servings of legumes, eggs, nuts, seeds or additional dairy products each day.

(sharing info)