Science- Middle aged people have the same calorie-burning potential as 20-somethings, new research suggests.
- While your
metabolism does slow from infancy through the teen years, it holds steady from age 20 to 60, the findings suggest. - One expert said the "pivotal" study calls everything we know about weight control into question.
Popular wisdom says that you can't keep eating like a 20-something in your 30s, 40s, and beyond - you'll start to gain weight because, we've been told, our bodies burn calories at a slower rate as we age.
That may not be the case, according to a study published August 12 in the journal Science, which found, from the age of 20, your rate of metabolism barely shifts until age 60.
More than 80 researchers across different labs pooled their resources to study data from 6,421 people across 40 years, to see how factors like age, size, and gender affect metabolism. The researchers used a technique called "a doubly labeled water test" to measure the carbon dioxide a person produces to gauge their energy expenditure.
They found that, while age does play a role in how quickly we burn calories, it doesn't dampen metabolism as much or as quickly as previously thought.
Leanne Redman, an energy balance physiologist at Pennington Biomedical Research Institute who was not affiliated with the study, told the New York Times that the findings are "pivotal."
"It will be in textbooks," Redman said.
Middle age, pregnancy, and even menopause had little impact on metabolism, the study found
The study analyzed human metabolism across four life stages - infancy to age one; one to 20; 20 to 60; 60 onwards - and found babies burn the most calories, proportionate to their size.
From there on, they found, metabolism starts to slow steadily until age 20, with a slight decrease of about 2.8% each year.
After age 20, metabolism holds steady for the next four decades, researchers found, finally beginning another gradual dip around age 60.
The researchers said it was surprising to find that factors like middle age, pregnancy, or even menopause didn't seem to change the ability to burn calories.
"We found no evidence to support that. So if you are piling the weight [on] and your waistline is expanding during your 30s and 40s, it's probably because you are eating more food, then expending less energy," John Speakman, co-author of the study and a professor at the University of Aberdeen, told the Guardian.
The findings could be crucial for helping scientists better understand important questions about metabolic