Eat like a horse
Definition 1 of 1
Pro Tip 1/3Non-literal Meaning
The phrase is an exaggeration and not to be taken literally. It indicates eating voraciously, not actually like a horse. 
When I saw him at the buffet, he was eating like a horse.
Pro Tip 2/3Focus on Quantity
Use the phrase to stress the large amount being eaten more than the manner of eating. 
Although she's small, she can eat like a horse.
Pro Tip 3/3Informal Context
It's informal and usually used in casual conversations, not in formal or polite settings. 
We need to prepare a lot of food for the picnic since Jake eats like a horse.