Being fat makes running less fun. So there's a pretty new study that suggests fat people's fat makes them less inclined to engage in running. No shit, obviously, but there's apparently an actual brain chemistry mechanism behind it. The TL;DR is that STAT3 is involved in dopamine rewards for running, and leptin interferes with it. The study also hypothesizes that falling leptin levels increases stamina and the dopamine rewards of running. TL;DR: Thin privilege is enjoying runner's high.