In the continued spirit of post-holiday reorganizing (I won’t say “resolutions”), here’s an interesting dieting tactic: Put your money where your mouth is. No, really.

Economist Richard McKenzie recently described a rather unusual incentive that he gave himself to lose weight. He signed a formal contract with a friend that required him to pay her $500 unless lost nine pounds within the next 10 weeks.

“After signing the contract, I was amazed at how the looming $500 payment affected my behavior,” McKenzie wrote. “While on my diet, I judged practically everything I ate in terms of how much it would ultimately cost me.”

(In the end, he lost 14 pounds.)