At a personal level, I can also say that it is flat out hard to eat large amounts of food if you are staying active.

I've never had that problem. When I exercise a lot, my body just starts to crave a higher proportion of calorie-dense foods - ice cream, cheese, breads. The actual volume of food might not go up all that much, but the balance changes.

Of course, "a lot" for me is 10-15 hours cardio/week plus 3-4 hours/week weight training. My baseline is 3-5 hours cardio and the same 3-4 weight training. I only ramp up to 10+ hours cardio if I have a major event planned (100 mile mtn bike race or similar).

I think it is safe to say that 10-15 hours of cardio a week is far far more than most people get. Hick, 6-10 hours of exercise a week is almost certainly multiples of what most people do. :D

But, yeah, I was meaning volume as well as certain types. As I understand it, at the elite levels, you actually have to train your body in how to consume enough to stay active for the full event. It isn't like you can just down a few cheese burgers and then head off to a race.

Ice cream remains an amusing one, to me. People are convinced it is among the worst snacks you can do, and yet I have yet to meet a very active person that doesn't love some form of ice cream on a regular basis.