Candace (groans): This must be what it feels like to be pregnant.
Candace's medieval counterpart, Candavere, along with her friends Stacehilda and Jenavene, gain some nice bulges after a large banquet at the end of Excaliferb: A Further Adventure. In fact, there are two drawings depicting these here and here.
Finally, in Two Lads in Dangrabah, Candace swallows a submarine sandwich whole, which causes her stomach to bulge out significantly. Because in this story, she is a genie, she uses magic to shift the fat in her gut into other places, but since she doesn't do this immediately, it appears that she doesn't seem to mind being bigger.
Funny, all three stories happen to be written by the same fanfic duo.
Sonic the Hedgehog's Rouge the Bat unknowingly fattens herself up in Rouge's Weighty Frustrations. She doesn't even notice her larger belly for quite some time, until she decides to go on a heist, where her new bulge gets her stuck in a small space... twice.
This happens to Dawn in the second chapter of the Total Drama fanfiction, Total Drama Prison. She drinks four whole bottles of aged soda as part of a challenge. Not only does her stomach bloat up and start aching, which lasts for the rest of the chapter, but she also gets the hiccups from drinking too much.
Plasma's Folly contains a non-comedic example: assuming his Zekrom form, a famished Ben swiftly devours a platter of food, swallowing whatever he can fit down his throat whole. This is good and fine, until he reverts to his human shape while retaining the contents of his stomach. Nearly leads to Death by Gluttony.