I'm going to get this guy's back here for a minute, because I've been there. 3 weeks is likely a bit of an exaggeration, but I myself went 8 days without a meal - I had food (small bits of bread, a little popcorn, but not much else) throughout that time, but not an actual meal - back in early 2008 (Great Recession).

3 weeks is 21 days, which is about half the time you'd need to die of starvation, assuming no other nutrient intake (and no water insecurity; you'll die in only a few days without water, even dirty water). That's likely not really what happened in this guy's case, since - and I speak from experience here - when you get that desperate, you get remarkably resourceful. Old multivitamins that you forgot were in the back of the cupboard and have sat there for at least 3-4 years? Yep, eat 'em. That freezerburned leftover scalloped potatoes at the bottom/back of the freezer from last year? Yeah, not the tastiest thing but it sure beats nothing. Out of everything else? Go see people at Sam's Club or Costco, or anywhere they give out free samples. Even a small bite can sustain you for a remarkably long time, much longer than you might think. The human body is _incredibly_ efficient; as a culture, we in the US eat just way more than we need (most of us, that is, myself included); so what passes for a "meal" for most of us, in a starvation context, could keep you going for 2-3 days.

So no, I don't think he's making this up, nor do I think it's sarcasm. I've been there. And take my word for it, because I hope you never have to find out for yourself, but the worst part of that scenario - being homeless or near-homeless, having no food - isn't the hunger. It's the fear.