Previous research as well as our own experience with people tells us that this cannot possibly be true, but this is where science vs real life experience can seem disconnected. However, the study was specifically looking for the metabolic rate of fat free mass and not the total metabolism. So, an individual with 20 pounds more muscle at age 20 than at age 60 would have a substantially higher total metabolism, without demonstrating a change in the metabolic rate of the fat free mass. And since the average American loses ½ pound of muscle per year during these years, this loss of 20 pounds of muscle is typical.
This research does illustrate that there are 4 ages when our metabolism is considered to be at a different level, but it also reinforces the message that our total body metabolism is directly dependent on the amount of fat free mass that we have. Which is all to say that our total body metabolism is determined by our metabolic rate multiplied by our mass, and muscle is an area of fat free mass that we have lots of control over. And the way to increase fat free mass of the body is by resistance training.
Remind your body that you want to keep the muscle. Challenge your body to develop more muscle.
And, as always, let me know how I can help.