Why is protein intake important?  Protein is broken down into amino acids  in the body.  Amino acids are the building blocks for your body.  They aid in re-building muscles, skin, hair, nails, the lining of your digestive tract, etc.  If your current diet is deficient in protein, your body will have to pick and chose what requires the most immediate attention – often leaving that sore muscle for a future protein intake.  Now consider if you wanted  to build muscle – this would almost be impossible on a protein deficient diet.