I'm 183lb and a 40" waist, and the Goodnites still fit me, people don't believe it, but I don't care, they work for me as they were intended for, yes they sit a little lower than on a kid, but they are still working fine, and I don't have a plumber crack when wearing them, so that means they fit if they cover up this part and they sit around 1" under my belly.
I sure know they wouldn't hold quite a lot of wetting like a lot of you like to do, but they work for me, I usually pee in them once or twice before taking them off. And 99% of the times I cover them with a cheap adult diaper from Wal-Mart, and I only see my Goodnites leak 2 to 3 times a month and the adult diaper cope with that so that does the trick along with adding extra bulk which is always a bonus, wish I could afford luxury premium abdl diapers, but they are out of my price range.