Any references are linked throughout the text below.

This might surprise you. It did me. I listened to a guy named Dr. Luc van Loon on Peter Attia's podcast the other day. He was talking about the loss of muscle's ability to assimilate dietary protein and build and maintain mass with age. What they call anabolic sensitivity, which leads to the muscle loss we see with aging. This was interesting to me, partly because I'm nearly 65, but also so I don't get too puffed up about the powers of testosterone. He did a study on guys with prostate cancer. They often give these guys androgen deprivation therapy which takes their testosterone levels to near zero so it won't feed a testosterone-sensitive tumor. What he found was even in these guys with no testosterone, he got them to uptake dietary protein into the muscle and build mass just by introducing resistance training, which is usually weight lifting. So, the good news, he says, is that you can still get an anabolic response in the muscles at age 70 and older. That is, as long as you have adequate protein intake, the right amino acid mix (with enough Leucine, Lysine, and Methionine), resistance training, and there are plenty of studies out there that show the gain in muscle responsiveness is better with healthy testosterone levels, but the point is activity is the more important factor of all and the muscle is still responsive at ALL ages. So get some resistance training in your schedule. Muscle mass is SO important to your health. It's shocking how quickly you lose anabolic sensitivity AND mass with inactivity. He took a group of healthy young people and put one leg in a cast and found a 35% reduction in anabolic response compared to the other leg after just one week of immobilization. Something to think about.