You may not notice it much at first, but as you get older your muscle mass will decrease even more, and your metabolism will slow down because of it. (verywellfit.com)
I got these products for researching their effectiveness in reducing body fat and tightening up my 57 yr old muscles. (101sarms.com)
As you grow older your muscle mass gradually decreases and so your metabolism will decrease as well. (shapesense.com)