We’ve all heard various versions of the same warning as we’ve gotten older:

“Wait until you reach your 30s. You won’t be able to eat like that anymore!”

“Once you hit 40, exercise gets so much harder!”

“Once you reach your 50s, you’ll gain weight, and everything will start to hurt!”

I’m 48 years old and, to be fair, I can’t eat like that anymore, exercise is more challenging, I have gained weight, and just about everything does hurt—and two years ahead of schedule!

However, the underlying implication of those warnings is that our metabolism is to blame and that the downward trends are inevitable. However, according to a new study, that does not appear to be the case.

Research recently published in the journal Science investigated daily energy expenditure throughout the human lifespan. The study was conducted by an international team of researchers who analyzed the daily caloric expenditure of more than 6,400 people worldwide. The participants’ ages ranged from eight days to 95 years old.

While most extensive studies have measured basal metabolism—how much energy the body uses to perform vital life-sustaining functions such as respiration and digestion—this accounts for only 50 to 70% of the calories people burn daily. This research also analyzed the energy burned to fuel all other activities, including planned exercise and daily living activities. Every calorie expended was accounted for, even those burned while fidgeting or thinking.

What the research team learned contradicts much of the “common knowledge” around the way metabolism changes as we age.

As you might expect, energy needs skyrocket during the first year of life, as babies burn calories approximately 50% faster for their body size than adults. Interestingly, while rapid growth during this period accounts for some of that increased metabolism, the calorie burn rate is not fully explained by the increase in weight. More research is needed to understand what drives the high metabolic rate during that first phase of life. After age 1, a person’s metabolism slows by about 3% annually until they reach their 20s.

Then, and here’s where things become counterintuitive, metabolism levels off and stay relatively consistent until around age 60. When body size was considered, even the growth spurt of adolescence and the changing physiology of pregnancy failed to drive an increase in metabolism. Even after age 60, metabolism declines relatively slowly, by only 0.7% per year.

When body mass is accounted for, the metabolism remains virtually unchanged from around age 20 to 60.

So, what’s going on here? A primary reason for the decline in metabolism is a reduction in muscle mass since muscle burns more calories than fat does. It appears that those physiological changes that occur as we pass from one decade into the next to have more to do with lifestyle factors and body-composition changes than with a naturally slowing metabolism.

What This Means to Health Coaches and Exercise Professionals

Some clients may throw their hands up in defeat when they think about getting older. However, this research shows that there is much more within their control than they might think. After all, if changes that were once perceived as an inevitable result of a slowing metabolism are more connected to our behaviors, then the results of this research should be a source of empowerment for clients.

Metabolism is the chemical changes in living cells that provide energy for vital processes and activities. Metabolism takes place on the cellular level and is impacted by countless factors, some of which are indeed out of a person’s control and others that can be positively affected through behavior change.

Variables out of our control include sex, genetics, and age. In addition, an endless list of variables that directly impact a person’s metabolism that health coaches and exercise professionals can address with clients, including not only nutritional intake and physical activity but also stress, sleep, rest, mental health, and the client’s overall happiness. 

Myers explains that this holistic approach addresses the whole person. “All of these elements are intertwined,” she says, “so it’s important to look at the big picture of overall health.”

Pete McCall, faculty in the Exercise Science Department at Mesa College, agrees with this approach and says communication is vital. While conversations about goal setting may not directly touch on a client’s metabolism, health coaches and exercise professionals should discuss the interconnectedness among the described variables. Yes, energy intake and expenditure should be the centerpieces of this conversation, but understanding the other factors is also vital. For example, stress management (or stress mastery, as Myers calls it) and sleep quality are linked to hormone production, which is directly related to metabolism.

Please take advantage of the goal-setting process and conversations during your sessions with clients to emphasize the importance of overall well-being and how the various elements of physical and mental health are intertwined and impact the way we age.

In Conclusion

Clients often believe that weight gain and declining health are part of aging. “They have been led to believe this is natural and inevitable,” explains Myers. And on some level, this is true, but it’s not due to a rapidly slowing metabolism throughout our lives. Instead, it occurs because people move less as they age.

It’s a vicious cycle and a self-fulfilling prophecy. People begin to gain weight or have some aches and pains, believe it’s part of growing older, so they move less because they think physical activity will exacerbate their pain or is a fruitless pursuit, which means they gain more weight and begin to feel worse.

Take a moment to think about the older people in your life. Some are probably relatively happy and healthy, while others are battling multiple health conditions and struggling to get through the day. McCall and Myers suggest that health coaches and exercise professionals help clients recognize the connection between lifestyle and overall well-being, including brain health, functional independence, and emotional and mental health. The intention here is not to imply that physical activity and better nutrition are cure-alls. But instead, to help clients feel empowered by the fact that their behavior can considerably impact their quality of life than they may have previously understood.

Myers says it’s up to health coaches and exercise professionals to help their clients clarify a vision of what they would like their lives to be like as they grow older and then ask, “How can you establish goals to set you up for that life?”

For McCall, it all comes down to “Stay active and stay strong.” If you do that, a lot of the other elements fall into place, he explains. Performing physical activity, particularly resistance training, can work wonders when it comes to countering the effects of aging and the reductions in muscle mass that accompany it. As stated, metabolism is directly linked to muscle mass, so maintaining or even building muscle as we age can help minimize or delay the harmful effects of the aging process, which for many people, is the ultimate goal.