I'm baffled by the take away from the study. If a sedentary person and an athletic person burn about the same, doesn't that just mean the sedentary person's energy is being spent on maintaining and accumulating fat mass? But why is that waffled about instead of stated?

Major Edit: more concise example

>As the athletes’ ran more and more over weeks or months, their metabolic engines cut back elsewhere to make room for the extra exercise costs, Pontzer says. Conversely, if you’re a couch potato, you might still spend almost as many calories daily, leaving more energy for your body to spend on internal processes such as a stress response.