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That Americans are sedentary at work and at home has long been a part of the explanation for the obesity epidemic.
For Britt Creech, this has meant getting creative with how she fits movement in her day.
In college, she played rugby for NC State. And in her early career as an engineer, she was also on her feet working with technicians on the manufacturing floor. But, that changed as she started advancing in her career.
“You’re just doing the day to day things from your desk, like invoicing, so you’re sitting a lot more.
And so naturally, my step counts were much lower than they had been,” she said.
This career transition is analogous to something epidemiologists call the obesity transition – as countries get richer, obesity becomes more prevalent. Today, over 40% of US adults are obese . Scientists are still puzzling over why.
Forager-horticulturalists in Bolivia and hunter-gatherers in Tanzania were compared to people from Nepal, South Africa, the US, and beyond. In all, 36 populations spanning 6 continents were compared. Despite the differences in development across groups, researchers found no real difference in energy expenditure, or calories burned.
Basically, those who hunt and gather for their dinner are burning as many calories as those of us who can afford to order it as takeout.
Yet, those in the developed world do have higher rates of obesity. If it’s not the lack of “calories out” that is causing obesity in the developed world, then it must be the other side of the energetic equation, “calories in.” Eating excessive calories is 10 times more influential than sedentariness in driving the obesity epidemic, the researchers say.
Physical activity has always been a part of public health guidance on obesity prevention from organizations like the WHO or CDC. But Herman Pontzer, professor of evolutionary anthropology and global health at Duke University, wanted to get more specific. His lab, the Pontzer Lab, was the one responsible for the PNAS study.
