Relatively speaking, one of these meals is healthier than the other one.

In what is perhaps a sign that a substantial portion of the iPhone-wielding public feels the need to test its dietary knowledge, Men’s Health today announced that users are gobbling up its “Eat This, Not That!” iPhone game. The app has accrued 500,000 downloads in 15 days, at one point reaching the No. 1 spot in the iTunes store’s Healthcare & Fitness category. It managed this feat by turning the task of selecting healthy foods into an amusing diversion.

More than just a series of digestive imperatives, “Eat This, Not That!” quizzes users by offering them two choices and asking them to pick the healthier choice. People who can choose the wiser of two Burger King options, for example, are rewarded with improved standing on a national scoreboard.

The game is based on its namesake book series, by Men’s Health editor in chief David Zinczenko and his coworker, food and nutrition editor Matt Goulding.

By the way, “Eat This, Not That!” won a Digital Ellie this year in the “Interactive Tool” category.