What is the origin of the idiom "eat like a horse" and when to use it?

The idiom "eat like a horse" has its origin in the behavior and appetite of horses and pigs. Horses are known for their large size, strength, and constant need for sustenance, while pigs are notorious for their voracious appetite and ability to consume large amounts of food. The idiom is used figuratively to describe someone who eats excessively or has a hearty appetite, emphasizing their seemingly insatiable hunger or the quantity of food they consume.