We Burn Just Half the Calories Other Mammals Do (2024)

Humans and other primates—with theexception ofthe tiny mouse lemur—have a signficant edge over other large mammals. According to new research, we require half the amount of energy to get through our day as a mammal of equal size. And it's thanks to this energetic advantage that we enjoy such long lives.

It also explains why,whileother mammalstake just weeks or monthsto grow up, it takes humans years and years.

A team of scientistsstudied energy expenditures of 17 primate species in zoos, sanctuaries and in the wild. They measured metabolic rate using an established method called "doublylabeled water," which involves dosing the study subjectwith aspecial isotopeof oxygenand watching howthe creature's system processes it into carbon dioxideover time. After collecting thisdata from primates, the researcherscompared it to known values for other mammals, taken from previously published studies. Controlling for body size, primates burn about 50 percent fewer calories than other animals, they found.

The team has no idea why primates burn so little energy. "What's more,the difference is not easily explained by differing activity levels: a human would need to run a whole marathon every day to be on an even energetic footing with mammals that aren't primates," the lead author told the New Scientist.

Surprisingly, the researchers also found thatthe primates housed at zoos and sanctuaries burned through the same amount of energyas those in the wild, the New Scientist adds. It's ahintthat there might be some energetic sweet spot that our bodies condition themselves to, regardless of what sort of lifestyle we lead.