CHICAGO (AP) — Want to work off those excess holiday pounds with a free fitness-club membership? Chow down on fast food first.

In an unusual marketing plan with New Year’s resolutions in mind, Bally Total Fitness Holding Corp. is teaming up with Louisville, Ky.-based Yum Brands Inc. to offer an unlimited number of four-week memberships at Bally clubs this winter.

The only requirement: Buy burgers, fries, pizza or the like at one of Yum’s more than 18,000 U.S. restaurants.

Customers who eat at any of five Yum restaurant chains – Taco Bell, Pizza Hut, KFC, Long John Silver’s or A&W Restaurants – during January can obtain a membership to one of Bally’s more than 400 nationwide facilities simply by presenting a proof-of-purchase receipt for any amount.

“As the new year approaches, many people start thinking about getting in shape,” said Marilyn Schorin, chief nutrition and regulatory officer for Yum. “What better way to help them achieve their New Year’s fitness resolution than to offer a free, four-week membership at the nation’s leading fitness company?”

Bally nutrition director Rob Wildman said the goal is to motivate and enable as many as possible to become more physically fit.

The marketing initiative also comes as increasing public health concerns about trans fats and obesity have put pressure on fast-food restaurants.

The passes must be activated by Feb. 7.

Yum is the nation’s second-biggest fast-food chain after McDonald’s Corp.