Every now and then, I read about an interesting societal trend that has implications for us investors. For example, several years ago, I learned that increasing rates of obesity in America were prompting changes from many businesses. Some airplanes, for example, were switching to wider seats, squeezing profitability (if not passengers) by accomodating fewer paying fliers on each plane. Southwest Airlines (NYSE: LUV) devotes a whole Web page to explaining its policy regarding "customers of size."

Perhaps less profit-pinching than widening airline seats is this example of a corporate reaction: Honda (NYSE: HMC) made the front seats in its 2006 Civic three-quarters of an inch wider than those in the 2005 model. At Ford (NYSE: F), car designers have been using "virtual mannequins" depicting passengers of various sizes, in order to reflect the fact that the average large man tacked on some 27 pounds between 1962 and 2000.

Statistics show just how widespread these concerns have become. According to the Centers for Disease Control and Prevention, two-thirds of Americans are overweight or obese, which is twice the rate of a generation ago. Estimates from the National Business Group on Health put the cost to corporate America at about $13 billion a year, when you consider additional health insurance expenses, sick leave, and other costs.

Profiting from big solutions
Yet some stocks are also profiting from obesity. Medical-device maker Stryker (NYSE: SYK), for example, is making specialized equipment to help medical professionals transport larger people, including those weighing more than 300 pounds. According to the Journal of Emergency Medical Services, sales of these stretchers are expected to grow to $50 million by 2012, nearly twice the level of sales in 2004.

Meanwhile, many employers are offering incentives to employees to get healthier. General Mills (NYSE: GIS), maker of my favorite cereal, Lucky Charms, offers its workers dozens of fitness programs.

If you see a trend under way, stop to think about how it might affect some companies as well. It's a good way to spot some stocks that could benefit from increased business.

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Longtime Fool contributor Selena Maranjian does not own shares of any companies mentioned in this article. Try our investing services free for 30 days. The Motley Fool is Fools writing for Fools.