As alluded to upthread by a couple of posters, it seems one needs a lot of extra calories to complete a period of sustained physical exertion, such as hiking the Appalachian Trail. I’ve sometimes thought it would be worth doing it just for the extra food I could scarf.
If anyone is curious, way back in 2008 I came up with a list, here on the SDMB, of what you’d have to eat in one day to consume 30,000 calories. I remember thinking it would be a five-minute project, but it took me much longer than I expected, as I wanted to list a variety of foods and not just say “30 Big Macs at 1,000 calories each.”