There's no rule etched in stone that says rock stars have to be skinny. There are plenty of folks who have succeeded in popular music who were on the large side: Van Morrison, Solomon Burke, the Conner brothers from the Screaming Trees, Leslie West, Aretha Franklin, the Fat Boys (duh), Heavy D, Black Francis, Meat Loaf, John Popper of Blues Traveler, the list goes on and on. If you can deliver the goods, who cares if you've had a few good meals beforehand?
Nevertheless, it's always somewhat shocking to see once-skinny stars chunk out. Probably most infamously, it happened to Elvis Presley in his latter years, but it also happened to folks like Ann Wilson of Heart, Stevie Nicks, and Mike Reno of Loverboy (see below), to name a few.
And now, it appears that Guns n' Roses singer/last man standing Axl Rose has gotten a bit on the large side, prompting plenty of "Fat Axl" jokes on the InterWebs. Of course, what's more of a joke is how long he spent working on that crappy Chinese Democracy album (13+ years). Dude could weigh 400 pounds for all I care as long as he recorded something close to Appetite for Destruction again. But the revolving lineups, sporadic and erratic concerts and seemingly endless tinkering have turned Rose into something of a laughingstock. Of course, he's always got the next album for redemption...so we'll look for that in 2021.