I forget where I heard this, but there's an old parable about an angel and a demon (or, maybe it's God and the Devil) walking down a street, not far from each other. At one point, the angel trips and falls, prompting the demon to rush over to the angel's aid. The angel is nonplussed, and inquires as to the motives of the demon. The evil one replies: "Without you, I cannot exist."

That was my line of thinking when I read the following press release detailing an interesting little promotion from Bally Total Fitness (NYSE:BFT) and Yum! Brands (NYSE:YUM). To celebrate the new year, patrons of Yum! assets like KFC, Taco Bell, and Pizza Hut can enjoy a four-week membership to Bally by presenting a receipt to the gym in any amount for purchases made in the month of January. I hope I'm using the term correctly here, because I remember the minor backlash Alanis Morissette received a few years back over it, but I find the proposal utterly ironic. I mean, people will go to Pizza Hut to get fat on pie and then head on over to Bally to become thin again? I am an occasional patron of Pizza Hut and KFC (in fact, I celebrated Christmas with a bit of the Colonel's cooking), and I have to say, if I'm going into one of these joints, I'm probably not going to head for the gym afterward, since the logical thing would have been to go to the gym first and bypass the fast food altogether.

That's not to say this isn't a smart initiative. For the most part it is, on a couple of different levels. Sure, there is the top, direct level of Yum! Brands adding value to its customers' visits and Bally receiving a spike in people sampling its wares, people who probably know they should be working off some of the greasy, fattening food they just ingested but never seriously contemplated heading into an exercise complex before. But, it also presents a nice image for Yum! Brands and its places of business. Fatty foods are being excoriated left and right these days, in a similar fashion to tobacco, with threats of litigation thrown about. Places like McDonald's (NYSE:MCD) and Wendy's (NYSE:WEN) know it is in their best interest to support strategies that spread the word on healthier living. Mickey D's, for instance, produced a healthier Happy Meal for adults that promoted walking (I picked up the meal this past summer to acquire the cool pedometer; it's fun tracking how many steps I make while walking for exercise). There really is a fascinating symbiosis here, in an angel/demon sort of way: Yum! Brands fattens people up so they require Bally's services, while Bally allows people to shed enough so the cycle can begin again.

I'm not sure how successful this promotion will be, but I suppose more than a few will be bringing their receipts for extra-cheese-in-the-crust pizza and overstuffed tacos to their local Bally location. And, hey, more power to them. I've never been to a gym in my life because the last thing I want is some fit fellow exerciser to see my gut heaving up and down on one of those stair-climbing contraptions. I will definitely continue visiting the local Yum! Brands outlets, though.

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Fool contributor Steven Mallas owns none of the companies mentioned.