I'm lucky, my mum is Irish and I got her potato famine genes. They say skinny people will be the first to go in a famine but I feel differently. My frame is slight (ankles and wrists in the bottom tenth percentile for males, despite me standing at average height, 5'10), and my stomach is small. Means I don't need many calories to survive and won't get hungry on reduced rations. My feeling is many of the large framed Irish died out.
I eat MacDonalds 4+ times a week and have junk food and lollies everyday, but even so, without dieting and eating whatever I want (junk) I'll naturally maintain a lean condition (circa 15 percent bodyfat, top two abs clearly defined and middle two also visible), as I just subconsciously self regulate my caloric intake and ensure I never eat enough to get myself into too much of a surplus. Whenever I do decide to cut the empty cals I get a ripped 6 pack (all abs in) without feeling too hungry, and the heaviest I've ever been, when I was on full bulk mode, was all of 185 pounds, max 20 percent bf (still lighter and leaner than the average yank and Aussie despite my junk food diet). Starvation genes.