There’s no question that America — and much of the developed world — has an obesity problem. What is debated is whether excess body fat is the result of moving too little or eating too much.
A new study led by an Elon University researcher points to an answer.
Amanda McGrosky, an assistant professor of biology at Elon, is the co-lead investigator on research that looked at the body’s energy usage in people all over the world. They included a range of lifestyles from urban dwellers to hunter-gatherers.
She used that data to address an age-old question: Are people in the developed world obese because they eat too much or because they sit too much?
“There weren’t really any differences in total energy expenditure across these populations,” she says. “So, someone who lives in a hunter-gather society who has 40 kilograms of lean body mass is going to expend the same energy as someone who lives in the U.S. and also has 40 kilograms of lean body mass.”
So why then do we have an obesity epidemic?
“The simplest answer here is that people are taking in more calories than they’re burning,” she says.
Still, McGrosky, a former swimmer, says diet and exercise are not an either/or consideration. She wants people to continue to move.
“Some of the headlines have been like ‘Oh, activity is not important.’ But I just want to emphasize that activity absolutely is important,” she says. “It’s not saying don’t go for a walk or don’t go for a little jog. It’s just, it might not be affecting your total energy expenditure — that bottom line of the number of calories that you burn on the long run.”
McGrosky’s team did not look at the kinds of foods people were eating. But she says ultra-processed calorie-rich foods are a problem, and the results point to the importance of access to high-quality food.