What with the news that almost every snack in Europe is actually my little pony, and the jokes about spaghetti bologneighs, I keep being asked about the origin of the phrase I could eat a horse. Specifically, does it mean:
1) I am so hungry that I could eat something as large as a horse, an elephant or a blue whale.
2) I am so hungry that I would be prepared eat something unusual, like horse, squirrel or cockroach.
So I set off to trace the phrase back. It turned out to be popular all the way through the nineteenth century. But once you get far enough, the phrase changes to I could eat a horse behind the saddle. This version pops up in the stage-play of Guy Mannering (1816) where it seems to be proverbial. The earliest reference I could find was in a book called The Life and Adventures of Sir Launcelot Greaves written by Tobias Smollett in 1760.
A chap is lying ill in bed and complaining about the medical treatment he has been receiving. I've highlighted the bits that I think are relevant:
"What do you chiefly complain of?"—"The doctor."—"Does your head ache?"—"Yea, with impertinence." "Have you a pain in your back?"—"Yes, where the blister lies."—"Are you sick at stomach?"—"Yes, with hunger."—"Do you feel any shiverings?"—"Always at sight of the apothecary."—"Do you perceive any load in your bowels?"—"I would the apothecary's conscience was as clear."—"Are you thirsty?"—"Not thirsty enough to drink barley-water." —"Be pleased to look into his fauces," said the apothecary; "he has got a rough tongue, and a very foul mouth, I'll assure you."—"I have known that the case with some limbs of the faculty, where they stood more in need of correction than of physic.—Well, my honest friend, since you have already undergone the proper purgations in due form, and say you have no other disease than the doctor, we will set you on your legs again without further question. Here, nurse, open that window, and throw these phials into the street. Now lower the curtain, without shutting the casement, that the man may not be stifled in his own steam. In the next place, take off two-thirds of these coals, and one-third of these blankets.—How dost feel now, my heart?" "I should feel heart-whole, if so be as yow would throw the noorse a'ter the bottles, and the 'pothecary a'ter the noorse, and oorder me a pound of chops for my dinner, for I be so hoongry, I could eat a horse behind the saddle."
Barley water was a standard medicine in the eighteenth century, and I can't find any reference to people drinking it for fun. I assume therefore that it tasted bad (and that it's rather different from the modern stuff).
Now, I don't know much about horses, but I'm going to assume that one that is saddled is sweating, and that the bit behind it is the backside. Not even in France do they eat sweaty horse poo. Not even in Verona.
So I'm going to say that the phrase I could eat a horse refers not to the size of the horse, but to its unusualness; and that it's roughly the equivalent of the American I could eat the tail end of a skunk.
I would be particularly amused if all the horse butchers in Verona were really selling beef.