A very fat man or woman. More guts than brains; a silly fellow. He has plenty of guts, but no bowels: said of a hard, merciless, unfeeling person.
Definition taken from The 1811 Dictionary of the Vulgar Tongue, originally by Francis Grose.
Guts * GutfounderedNathan Bailey's 1736 Dictionary of canting and thieving slang
John S. Farmer's collection of canting songs and slang rhymes