Any bodybuilder with a rudimentary understanding of the sport would know the key to gaining muscle is protein consumption. But how do we know if we are getting enough protein? You can find out here along with information on proteins and amino acids. Any bodybuilder with a rudimentary understanding of the sport would know the key to gaining muscle is protein consumption. Granted, training, rest and other nutrients all enhance anabolism, and growth, but protein (being the key size-building nutrient) is absolutely essential when it comes to packing it on - 60-70% of bodily protein is found in muscle. In fact, protein is the key "building" nutrient for a variety of bodily tissues, many of which support muscle growth (enzymes, skin, hair, nails, bones, and connective tissue are all constructed from protein). Protein makes up 15-20% of one's bodyweight and is thus, next to water, the body's second most abundant substance. Most Popular Bodybuilding Supplement . ...