Middle-aged male doing high knees in an open field.

Your Metabolism Slows With Age. Just Not When You Think

You’ve probably heard the age-old notion that metabolism slows down as you age. The idea explains why weight loss is such a bitch as you get older. It’s not that sleeve of Oreos you (I) ate when no one was watching, it’s your metabolism. Right?

Wrong. Your metabolism doesn’t slow down as you age, at least not between the ages of 20 to 60 suggests new research from the journal Science (1).

Herman Pontzer, a professor of Evolutionary Anthropology at Duke University, and a team of scientists investigated the impact of people’s age compared to their daily calorie burn. Their findings were fascinating, if not a bit of a bummer.

What Did The Study Find?

As the first extensive study of its kind, Pontzer’s team tracked and compared the total calorie expenditure of 6,421 participants of all ages from 29 countries.

From the Hadza hunter-gatherers of Tanzania to the Tsimane farming villages in Bolivia and everything in between, they found (as expected) that metabolic rates increase with body size: bigger bodies burn more calories.

They also found, “the greatest predictor of metabolism is fat-free mass,” according to Pontzer in Scientific American. Fat-free mass is made up of your muscles and organs—tissues that contribute the most to your daily energy expenditure.

Though women are commonly thought to have slower metabolisms than men, Pontzer’s team discovered that this is simply because they are smaller and tend to carry more fat. “Compare men and women with the same body weight and body fat percentage, and the metabolic difference disappears,” Pontzer explains.

Metabolism Does Slow With Age, Eventually

“Perhaps the biggest surprise was the stability of our metabolism through middle age. Daily energy expenditures hold remarkably steady from age 20 to 60,” Pontzer wrote in Scientific American. “The weight gain so many of us experience in adulthood cannot be blamed on a declining metabolism.” Anyone else feeling called out?

Your metabolism does eventually slow down, just not until your 60th birthday when it declines at a rate of 7-percent per decade. “By the time men and women are in their nineties, their daily expenditures are 20 to 25-percent lower, on average, than those of adults in their fifties. That’s after we account for body size and composition,” Pontzer said.

How to Increase Metabolism

This research provides what Pontzer dubbed a “metabolic road map” for further research when it comes to keeping a speedy metabolism in your older years.

What we can glean from current research? Your fat-free mass plays a big role in metabolism. To increase it, regularly engage in strength training.

Strength training has been definitely proven to increase lean muscle mass (fat-free mass) (2). Plus, skills developed from regular strength training like balance (3) and grip strength (4) have been linked to a longer, healthier life, too.

1. Pontzer, H. et al (2022). Daily Energy Expenditure through the Human Life Course. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8370708/
2. Krzysztofik, M. et al (2019). Maximizing Muscle Hypertrophy: A Systematic Review of Advanced Resistance Training Techniques and Methods. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6950543/
3. Araujo, C. et al (2021). Successful 10-second one-legged stance performance predicts survival in middle-aged and older individuals. https://bjsm.bmj.com/content/56/17/975
4. Peterson, M. et al (2022). Grip strength is inversely associated with DNA methylation age acceleration. https://onlinelibrary.wiley.com/doi/full/10.1002/jcsm.13110