The following is a summary of a story that originally appeared on the School of Medicine website. Photo by Eamon Queeney.
Evolutionary anthropologist and DUPRI Scholar Herman Pontzer explains why exercise isn't the calorie-burning machine many people assume it to be — and why that's not a reason to dismiss it. Pontzer's research has shown that daily energy expenditure stays within a fairly narrow range even when physical activity increases dramatically. For example, Pontzer spent time in Tanzania living among the Hadza, a traditional hunter-gatherer community. He was surprised to find that hunter-gatherers who walk long distances each day burn about the same number of calories per day as sedentary people in industrialized societies. This happens because the body compensates: when you increase physical activity, it reduces energy spent elsewhere — on immune function, reproduction, even stress responses, keeping the total energy used roughly constant.
Pontzer reframes how we think about diet and exercise. "You have to think about diet and exercise as two different tools for two different jobs," he says. "Diet is the tool for managing your weight. Exercise is the tool for everything else related to health — from mental health to cardiometabolic disease."
Instead of focusing on exercise as a means to burn more calories, Pontzer emphasizes its broader health benefits — from lowering chronic inflammation to reducing disease risk — and points out that metabolism evolved not for excess calorie burn but for survival and flexibility in the face of scarcity.
To read more, go to the School of Medicine website.