I would say that in practice 99% of people can't outrun a bad diet, but not because of any sort of physiological reason. You simply need to train so much that most people won't ever approach the level of running/cycling/lifting they would need to do so.

If you're training like an elite athlete (for me and my at the time roommate that was running 85, or in his case, 100+ miles a week with a few lift sessions) you can, and will, eat just about whatever you damn please and not gain weight. Most people can't fit that much training into their lives without making it their life's primary focus at the expense of everything else, and couldn't sustain that level of training if they did, so it becomes a practical impossibility.

I do miss that aspect of running so much mileage, though I appreciate the freedom that stepping back from competition has afforded me in other areas. To maintain weight now, I eat 1-2 meals a day, but back then? I ate whatever got put in front of me, sometimes 4 meals a day.

Sure but for the purposes of mass communication or creating helpful and memorable aphorisms "you can't out run a bad diet" is an appropriate summarization of the research.

If it's all ppl get out of it, the worst that might happen is that a handful of up & coming elite athletes might need their coaches to help them unlearn it, as opposed to the status quo where literal millions of ppl are trying & failing to outrun their diets.

Right, and that's fine. A saying that's true for 99% of people is a perfectly good saying. In the vast, vast majority of cases, "you can't outrun a bad diet" is completely true.

Your time running 85 miles a week is so outside the norm that your experience isn't even worth mentioning when evaluating that saying.

> you can, and will, eat just about whatever you damn please and not gain weight

I don’t know if any athlete who can sustain themselves on a junk diet.