“You and I have a tendency towards corpulence. Corpulence makes a man reasonable, pleasant and phlegmatic. Have you noticed the nastiest of tyrants are invariably thin?”

— Gracchus, “Spartacus”

The biggest culture war in America may not, in fact, be between conservatives and liberals, or even Auburn and Alabama fans.

Instead, the cultural clash that appears to be gaining the most steam is between fat and thin.

In popular media, as well as in the real world, the two sides jockey for position. “Get in shape!” “Eat like a man!”

You get the idea.

On the thin side, new ways to stay thin gain steam every hour. Plans like the “Couch to 5K” have become very popular, along with home workout devices like the reprehensible P90X.

The thin patrol has even found a way to make video games good for you, with the advent of Nintendo Wii (and its accessory, the “Wii Fit”).

With all this fitness, you’d think our country would be among the healthiest around the world. And you’d be dead wrong (in some cases, quite literally).

By every statistical measure, Americans are heavier now than ever — Birmingham, in fact, rated as America’s second-most obese city in 2007, right behind Memphis (which shouldn’t really count because … I mean, you’ve been to Rendezvous, right?).

How is this possible? The answer: The people making the food keep coming up with new and extraordinarily inexpensive ways to make America fat.

The latest incarnation is KFC’s “Double Down,” described on its Web site thusly:

“This one-of-a-kind sandwich features two thick and juicy boneless white meat chicken filets (Original Recipe® or Grilled), two pieces of bacon, two melted slices of Monterey Jack and pepper jack cheese and Colonel’s Sauce. This product is so meaty, there’s no room for a bun!”

(Read that paragraph again, in case you didn’t get the full effect the first time.)

The big catch: Eating healthy requires more money. Eating Double Down sandwiches barely requires pocket change.

Is it better to be healthy and broke? I have no idea.

It’s not hard to switch sides in this debate. After spending most of my high school and college days as a way-too-thin dweeb, I converted during my first newspaper job into much-too-large dweeb. I’ve been attempting to straddle the fence ever since, which usually involves three hours of soul-crushing exercise, followed by a massive dinner of fried grease.

It’s the heartbeat of America. At least for now it is.