The report found obesity is associated with a 36 percent increase in health-care spending, more than results from smoking or alcoholism. Since 34 percent of American adults fit the definition of obesity, cutting costs associated with the condition will challenge companies for years to come.

“Employers need to pay attention to their workers’ weights, for the good of the bottom line, as well as the good of the employees and of society,” said Linda Barrington, a labor economist and research director at the Conference Board.

Companies are gearing up to combat obesity.

The report said that more than 40 percent of U.S. companies have obesity reduction or wellness programs, and an additional 24 percent plan to start such programs in 2008. The programs can yield a return on investment from ranging from zero to as much as $5 for each $1 invested.

But throwing money at such programs can also add to employers’ woes.

Companies risk discrimination lawsuits if they are too forceful about encouraging employees to manage their weight, even if it is for the employees’ own good. And not all weight loss and obesity programs get results, which could leave employers stuck with a weighty bill.

The report suggested companies involve their employees in the planning of any health initiatives, before programs are put into place.

Filed by Matthew Scott of Financial Week, a sister publication of Workforce Management. To comment, please e-mail editors@workforce.com.