In physically inactive people there is a loss of about [-0.5%] of lean muscle mass every year between age 25 and 60, and a corresponding decline in muscle strength. From age 60 on, the rate of loss doubles, to about 1%. It doubles again at age 70; again at age 80, and then again at age 90. With age we are losing muscle mass, and that muscle mass is being replaced by fat cells. … [Read more...]