Everyone older than 40 is naturally losing muscle at a rate of ~0.8% per year (1). If you do not eat high quality protein and do not workout, your quality of life will be significantly decreased when you get old by falls and loss of ability to perform activities of daily living. The roles of skeletal muscles are not only locomotion and power production but include metabolic regulation so that loss of muscle mass increases risks of metabolic syndromes including type II diabetes and cardiovascular disease.The good news is that you can grow muscle even in old age by combination of quality meals and resistance exercise. The keywords for this are essential amino acids (EAAs), branched-chain amino acids (BCAAs) and resistance exercise.