The blushes and the jealous looks of the men and jacks around you do it. "HEEEEE-HAWWWWWWW!!!!" You let out a deep rugged bray that vibrates your whole body and causes fur to rush up the rest of your body.
"Need...fatter..." You say, brain dulling by the second.
"Right this way jackass!" The man says, revealing a trough of oats. You plunge your face into the food without thought. You can feel your belly barreling out to make room for the food, ripping your shirt away. Your arms stretch, and your hands go numb, but you don't care, hooves are better than hands for how you live. You clop them to the floor and go back to eating.
At last the moment you have been waiting for comes, you feel your muzzle extending, making it easier to eat.
The man looks into your eyes and smiles as he sees dull equine orbs. You ignore him though. Food is all you care about.