Eat like a bird or horse?

 How much does a bird eat?

Not very much, right? So, to eat like a bird is to eat very little.

Don’t trouble yourself cooking varieties. I eat like a bird.

 

Now, a horse is much bigger than a bird. So, how much do you think a horse eats?

That’s right, to eat like a horse is to eat a large amount of food.

 My mother has to cook a lot of food when my brother comes to visit. He eats like a horse.