Researchers assessed the amount of calories burned per day in 17 primate species ranging from gorillas to mouse lemurs. They lived in zoos, sanctuaries and in the wild.
"The results were a real surprise," study author Herman Pontzer, an anthropologist at Hunter College in New York City, said in a college news release.
"Humans, chimpanzees, baboons, and other primates expend only half the calories we'd expect for a mammal. To put that in perspective, a human -- even someone with a very physically active lifestyle -- would need to run a marathon each day just to approach the average daily energy expenditure of a mammal their size," he explained.
The study also found that primates in captivity burn as many calories a day as those in the wild. This suggests that physical activity may have less of an impact on daily energy expenditure than previously believed, the researchers pointed out.
The findings, published in this week's issue of journal Proceedings of the National Academy of Sciences, could help improve understanding of human health and longevity.
For example, connecting the rate of growth, reproduction and aging to daily energy output may increase knowledge about the processes behind body development and aging. And further investigation into the relationship between physical activity and daily energy expenditure may improve understanding of obesity and other metabolic diseases, according to the researchers.
The investigators are now taking a closer look at energy output, physical activity and aging among humans and apes.
"Humans live longer than other apes, and tend to carry more body fat," Pontzer said. "Understanding how human metabolism compares to our closest relatives will help us understand how our bodies evolved, and how to keep them healthy."
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