This shocking discovery may change the way we think about metabolism

• Metabolism doesn’t really change until you’re 60, according to a new study.
• It peaks when in infants — when you have the highest metabolic rate.
• This doesn’t mean you can start eating anything you want now.

What you thought you knew about metabolism is probably wrong.

We’ve been told that metabolism — the rate at which you burn calories – decreases as time goes on; burning calories and shedding weight becomes more difficult as you age. That’s why many of us watch what we eat since at some point adding weight becomes tough because we can no longer burn it off as easily.

The period of food-watching, which often begins in middle life, may not be needed any longer.

A new international study claims to have broken the metabolism myth by proving that metabolism’s inevitable fall doesn’t really begin until we’re in our 60s.

“There are lots of physiological changes that come with growing up and getting older,” said study co-author Herman Pontzer, associate professor of evolutionary anthropology at Duke University. “Think puberty, menopause, other phases of life. What’s weird is that the timing of our ‘metabolic life stages’ doesn’t seem to match those typical milestones.”

When does metabolism start declining?

The study, published in the journal Science, used data from nearly 65,000 people, ranging between the ages of one-week old and 95-years old. By combing through responses from respondents in 29 countries, researchers determined that metabolism only really changes in four stages of life.

“People thought, ‘Well, maybe it’s because you’re less active, or maybe it’s because people tend to lose muscle mass as they get into their 60s, 70s and older,’ ” Pontzer told NBC News. “But we can correct for all those things. We can say, ‘No, no, no, it’s more than that.’ It’s that our cells are actually changing.”

In fact, metabolism actually peaks much earlier in life — like right when you were born. Researchers found that pound for pound, infants had the highest metabolic rates of all participants. A one-year-old can burn calories 50% faster at their body size than an adult.

Gradually, metabolism declines around 3% each year until you’re about age 20, where it then plateaus. It’s not until you’re 60 that it really starts to decline again, which according to the findings, is by less than 1% annually.

“Metabolic rate is really stable all through adult life, 20 to 60 years old,” Pontzer said. “There’s no effect of menopause that we can see, for example. And you know, people will say, ‘Well when I hit 30 years old, my metabolism fell apart.’ We don’t see any evidence for that, actually.”

Does this mean I can eat whatever I want?

Not quite.

“[The results] do not make much of a difference for everyday people,” said Dr. David Buchin, director of bariatric Surrey at Northwell-Hungtington Hospital. “There is a morbid obesity problem in our country and people still need to diet, exercise. This study should not make people approach their weight loss any differently, they still need to diet and exercise to maintain weight loss.”

The Centers for Disease Control and Prevention recommend that adults get 150 minutes each week of physical activity. They also have guides for healthy eating which focus on fruits, vegetables, whole grains, and other foods.