Even if they do have jobs or relationships, all they do at home is sit on the couch. I live with a fatty - didn't really have a choice at the time, and working on getting out of here now that I'm graduated - and she comes home from work and then sits on the couch. Sometimes she sleeps there, too. And that's pretty much all she does: sit at her computer and look at stupid shit on the internet. At least when she was a smoker she'd have to get up and go outside, walk around a bit. But since her totally-not-obesity-related quadruple bypass earlier this year (she's... mid to late 30's), she gave up smoking, and with it any semblance of exercise she got.