Of course, any male who saw Disney’s Fantasia in his adolescence has a bit of a centaur filly fetish.
It may be a sign of my geekiness, however, that even as a besotted teenager, I had a bit of literal “refrigerator logic”. To wit, “How do they eat?”
Today, with the Webz and all, I had the opportunity to work out some rough calculations.
To start with, A 1000 pound horse requires about 15,000 Calories a day, that’s big-C Calories. Horse digestive tracts are very inefficient, and require about 25 pounds a day of mixed fodder, that is, forage (hay) and concentrate (oats, molasses, corn, and the like). Obviously, there’s no way for a human mouth, with human teeth, to chew through 25 pounds a day of horse feed.
And let’s not talk about grazing with a flat face.
Of course, the far more efficient human digestive tract can eat much more concentrated foods, like meat. Maybe that helps. Accordingly, the following numbers are based on scaled-up human internals.
A pound of sugar is 1760 Calories. That means that a centaur eating pure sugar needs about 8-1/2 pounds of sugar every single goddamn day.
A pound of fried bacon is 2448 Calories; a carnivorous centaur would want about 6 pounds a day. (I choose bacon because a] it’s tasty and b] it’s a nice mix of protein and fat.)
Then there’s fiber. A human on a 2000 C/day diet needs about 25 g/day. Converting to pounds and scaling up to 15,000 C/day yields about 1/2 lb/day of pure, indigestible fiber. “I buy ‘er books and buy ‘er books and she just eats the cov… uhp, nope, just swallowed the whole damn thing. ”
Hah, hah, nobody eats books! So let’s look into apples…. Holy, uh, crap. There’s about 0.7 g of fiber in an apple. Converting to pounds, that’s in excess of 320 apples a day to keep the vet away.
But at least you now have an excellent excuse to wash down your meals with, yes:

…A bacon beer mug, which will help a little with the 8 or 10 gallons a day of water a lightly worked horse will need. Or, hey, splurge, and have a candied bacon ice cream float for dessert.
Of course, no body eats exclusively any one kind of food.
A Big Mac is about 540 Calories. Now, a Big Mac contributes to nutrition in several different ways, but going by calories alone, my hooved belooved would not be a cheap date: she’d need about 27 a day, at a cost of around a hundred bucks.
If she wants fries with that, she’d need about 13 Big Mac meals with medium fries and Coke. That’s a bit of a savings, only $80.
The dietary math is a little easier if your centaur chassis has a pony form-factor. Multiply everything by about 0.7, but remember, equines can only carry about a fifth of their weight. I’m too heavy for a 1000-lb horse; only a very lean young man, weighing at most 125 lbs, could ride his 700 lb pony girlfriend.
[update]
And speaking of ponies, note that Disney’s fillies are not only very small ponies, but lack the pot belly evident on real ponies. They have human digestive systems, not equine, and indeed, they later appear at a human-style banquet — although not with centaur-sized portions.
I was referred to Celesta, a photo-morphed image by “The Phantom Inker” of a lady centaur. Note how her human torso seems way too small for the horse body. She would be better proportioned as a pony. I may have to fool around with that.

[/update]
Then there’s breathing. The breath-to-breath measurement is called tidal volume.
For humans, tidal volume is about 0.5 liters.
For horses? About 6.0 liters, twelve times what a human needs. That means nostrils, and a windpipe, about four times the diameter of a human’s. And those are resting values.
So, conclusion?
No. Hell, no. You can’t eat like a horse, or even breath like a horse, through a human mouth.
Update:
Heh. I’m pointed to this episode of The Wotch. The young lady is a centaur who hides her equine body with an invisibility spell; we, of course, are not affected.

