Your body uses protein to build and repair muscle tissues, make the necessary enzymes, hormones, and other body chemicals, as it is an important building block of bones, muscles, cartilage, skin, and blood. Lean Beef, Skinless Chicken. The traditional option for protein. You can eliminate most of the saturated fat by removing the skin. Fish. High in protein, low in fat, and rich in omega-3 fatty acids, contains less fat than meat and aids in fat loss.