Protein, while used to build structure (muscle) and ____ enzymes, can also be used to provide energy. Amino acids ____ upon their ____, they can either be ____ to carbohydrates or fat. Our main ____ of protein are meat & fish, dairy products, nuts, eggs soy and ____ such as tofu. Body builders often use ____ milk (whey) and soy protein to ____ muscle. Our body can also synthesize some ____. The ones that we must get from our diet are called ____ amino acids.