Fat is big news, whether it's our country's Borg-like Atkins-ization or the recent American Medical Association study predicting that weight-related medical problems will soon surpass smoking as the nation's No. 1 preventable killer.

The usual whipping boys are fast-food restaurants like McDonald's (NYSE:MCD), Wendy's (NYSE:WEN), and Yum! Brands (NYSE:YUM). Yesterday, despite the utter failure of every recent obesity lawsuit, these enterprises came a step closer to national judicial immunity.

The U.S. House of Representatives passed the "cheeseburger bill," which prohibits obesity lawsuits and puts the weight-gain blame squarely on John Q. Supersize. Brushing aside the sad but amusing irony that the key proponents, Congressmen Ric Keller and Dennis Hastert, look like they have their own cheeseburger issues, let's look at why this matters to investors.

Companies spend big bucks dealing with overweight employees -- who now make up two-thirds of America's population. Oddly enough, the same corporate culture that applauds frivolous legislation like the cheeseburger bill has also made a tacit admission that Americans are ill-equipped to stand up to the food industry's marketing machine and curb their own eating.

The National Business Group on Health has funded a special institute to try to deal with the huge costs -- in lost productivity, insurance, and medical treatment -- that come hand in hand with America's incredibly expanding workforce.

NBGH members include companies that -- if they didn't have to pay for our health insurance -- would love to see us with our noses in the feedbag 24/7. A few are: Altria Group, Campbell Soup, General Mills, Kellogg (NYSE:K), Coca-Cola (NYSE:KO), PepsiCo, Sara Lee (NYSE:SLE), Sodexho, and rising grocery kingpin Wal-Mart (NYSE:WMT).

While I applaud their efforts to slim down their employees, I regret that the ultimate catalyst is cash, not conscience. As the costs of America's food addiction return to roost on the cash flow statement, I hope corporations will realize that they are only beginning to reap what they have sown.

Cheesecake queen Sara Lee is one of Mathew Emmert's Motley Fool Income Investor recommendations. Check it out, free, for 30 days.

Fool contributor Seth Jayson gets to eat whatever he wants because he can't kick the running and biking habit. He owns no stake in any companies mentioned above. View his Fool profile here.