Protein is a “macronutrient,” meaning that the body needs relatively large amounts of it. Protein is an important component of every cell in the body. Hair and nails are mostly made of protein. Your body uses protein to build and repair tissues and to make enzymes, hormones, and other body chemicals. Protein is an important building block of bones, muscles, cartilage, skin, and blood. Protein can also help you lose weight and belly fat while increasing your muscle mass and strength, children need protein rich diet for growth.