Red Lobster is famous for its 'Endless Shrimp' promotion. For $15.99 in most cities, you can eat all the shrimp you want.

But one man recently posed an interesting question on Reddit: how much food would you have to eat for Red Lobster to lose money?

A commenter whose brother-in-law worked as a restaurant manager gave an estimate:

"I called him, he said that it differs restaurant-to-restaurant. His store buys the shrimp wholesale at $4.55/lb for 31-35 shrimp per pound. He said that the other ingredients, including fry oil are negligible, and probably a few pennies per pound of shrimp. He guesses total cost to you on your plate is around $5/pound, including plates, cook's pay, etc.

So, at $5/pound, you'd need to eat a little over 3 pounds, or about 100 shrimp, to make it a net loss. He said even if you came in and ate 100 shrimp they would probably still make money because you will come with other people or you will order a drink or something. He has had two customers that have done it."

In other words, it's pretty much impossible for Red Lobster to lose money on your "Endless Shrimp" order.

DON'T MISS: 13 Fast Food Items With Fanatical Cult Followings >