Research review: Metabolism and aging

Spoiler alert! Your metabolism isn’t getting slower.

If there’s one thing this fitness and nutrition professional has heard time and time again, it’s the common thought that metabolism slows down with age. A person gets older, and they begin to gain weight, though they are eating less. They have more body fat, but are busily doing outdoor work and recreational activities like hiking and golfing.

Contrary to popular opinion, new research shows that our metabolism doesn’t slow down with aging; in fact, it really doesn’t change. This research provides a very good explanation as to why someone is gaining weight, by revealing the true relationship between metabolism and aging.

Metabolism is the rate at which a person’s body burns calories. It’s tied to gender, body composition, organs, and the basic life support of heart, brain, and lungs working tirelessly in the background. It varies from person to person but there’s not as much variability across the board. These calories account for 50-70 percent of the daily calories a person eats. Metabolism doesn’t include calories from activity, moving, thinking, or other functions other than basic life support.

A study from Pennington Biomedical featured an international team assessing 6,600 participants ranging from infants to 95-year-olds, from 29 different countries. They studied the average amount of calories people used and controlled for variables. The results: Metabolism remained the same from ages 20-60; thereafter, there is around a 0.7 percent decrease year to year.

Where does this leave the lamenting agers who swear they have a “slow metabolism”? It’s not actually metabolism to blame. In fact, unless a person is doing exercise to preserve muscle mass, after the age of 40 one begins to decline. Without this muscle mass, we aren’t requiring as many calories. Also, as we age we’re likely moving about less. A mother, while raising kids, likely did more on her feet than as an empty-nester. There was once a calorie expenditure that is not present in her current status.

This leaves the aging person with less activity and less muscle mass. If they are eating just as much as always, they will gain body fat. This will be argued with statements like, “I garden, walk the dogs, and clean up all the time.” While this may be true, a person with less muscle mass still needs less calories.

Before giving up to the “metabolism” woes, think of how we really age, and how behavioral change actually drives the mechanism. There is now research to prove this, and it’s all the better reason to begin a diet and exercise overhaul before it gets too dire.