Pooling and analyzing energy expenditures across the entire lifespan revealed some surprises. Some people think of their teens and 20s as the age when their calorie-burning potential hits its peak. But the researchers found that, pound for pound, infants had the highest metabolic rates of all.

Energy needs shoot up during the first 12 months of life, such that by their first birthday, a one-year-old burns calories 50% faster for their body size than an adult.

And that’s not just because, in their first year, infants are busy tripling their birth weight. “Of course they're growing, but even once you control for that, their energy expenditures are rocketing up higher than you'd expect for their body size and composition,” said Pontzer, author of the book, “Burn,” on the science of metabolism.

An infant’s gas-guzzling metabolism may partly explain why children who don’t get enough to eat during this developmental window are less likely to survive and grow up to be healthy adults.

“Something is happening inside a baby’s cells to make them more active, and we don't know what those processes are yet,” Pontzer said.

After this initial surge in infancy, the data show that metabolism slows by about 3% each year until we reach our 20s, when it levels off into a new normal.

Despite the teen years being a time of growth spurts, the researchers didn’t see any uptick in daily calorie needs in adolescence after they took body size into account. “We really thought puberty would be different and it’s not,” Pontzer said.

Midlife was another surprise. Perhaps you’ve been told that it’s all downhill after 30 when it comes to your weight. But while several factors could explain the thickening waistlines that often emerge during our prime working years, the findings suggest that a changing metabolism isn’t one of them.

In fact, the researchers discovered that energy expenditures during these middle decades – our 20s, 30s, 40s and 50s -- were the most stable. Even during pregnancy, a woman’s calorie needs were no more or less than expected given her added bulk as the baby grows.

The data suggest that our metabolisms don’t really start to decline again until after age 60. The slowdown is gradual, only 0.7% a year. But a person in their 90s needs 26% fewer calories each day than someone in midlife.

Lost muscle mass as we get older may be partly to blame, the researchers say, since muscle burns more calories than fat. But it’s not the whole picture. “We controlled for muscle mass,” Pontzer said. “It’s because their cells are slowing down.”

The patterns held even when differing activity levels were taken into account."

“Of course they're growing, but even once you control for that, their energy expenditures are rocketing up higher than you'd expect for their body size and composition,” said Pontzer, author of the book, “Burn,” on the science of metabolism.

...but it's still pretty cool to know that metabolism doesn't actually decrease that much as we age. More folks should hear that.

That actual study was fine, but the reportage, as usual, is BS data collation masquerading as "science."

Excerpt:

• Quoting:

Not if you recognize that the brain consumes 25% of our daily calories, that the infant brain is a miraculous supercomputer processing near infinite quantities of data every waking second, that the brain doesn't stop this evolution until around 20, that chess grandmasters can burn 6,000 calories in a single 4-hour match without moving from their seat, and that metabolism comprises a lot more than the size of our bellies.

...but it's still pretty cool to know that metabolism doesn't actually decrease that much as we age. More folks should hear that.