I get that, but I feel like we've known for quite a while that people who exercise can run longer and have lower body fat, regardless of genetics. Genetics can affect how long you can run compared to others, but you will run longer if you exercise than if you don't.

If you take anybody in the world and have them exercise, they'll lower their body fat, everything else being equal, no? And that's not only the same genes, it's actually the same person.