Protein is a macronutrient that is essential for every cell in the body. It is the building block for your muscles, cartilage, bones, skin and blood. Protein also helps in repairing damaged tissues. Your hair and nails are majorly made up of protein. Also, it is required to make enzymes, hormones and other body chemicals. It is recommended to have 0.8 gm protein per kg of your body weight everyday.