A big colleague costs more not only on the matter of space, but also in injury claims. A new research shows that obese workers presented a double rate of compensation compared to their fit counterparts.

The 8 years research made by a team at Duke University on a pool of 11,728 subjects revealed that the fattest employees lost 13 times more workdays connected to work-related injuries, and their medical costs for those injures were seven times more costly than in the case of lean employees. Obese employees were more exposed to back, wrist, arm, neck, shoulder, hip, knee and foot injuries than their colleagues.

Researchers found that workers with higher body mass indexes, or BMIs, had higher rates of workers' compensation claims. The most obese workers, possessing the highest body mass indexes (BMIs) of over 40 or higher also had the most costly compensations and the highest number of lost workdays.

BMI correlates height and weight: a 6 ft (1.8 m) tall person weighing 300 pounds (120 kg) has a BMI slightly over 40.

"The findings should encourage employers to sponsor fitness programs. There are many promising programs. We'd like to see more research about what is truly effective." said co-author Dr. Truls Ostbye.

"Managers will pay attention to the findings because injuries mean more immediate financial losses than the future health-care costs of diabetes and heart disease. When you see that claims rates double, I think that's going to get people's attention," said James Hill, head of the Center for Human Nutrition at the University of Colorado.

"But there isn't enough good information about employer-sponsored programs that work," said John Cawley, an expert in the economics of obesity at Cornell University.

"Employers don't know whether paying for nutrition counseling, obesity surgery or anti-obesity drugs through health insurance makes economic sense. It's now apparent to everybody that obesity is a big problem. But the research isn't there to know where to get biggest bang for the buck." he added.

BMI also is not an effective measurement of body fitness: it does not make the difference between muscles and fat tissue, equalizing a massive body builder to a couch potato. This study has discovered that blacks are particularly vulnerable to be misclassified by BMI. "Employers need to be careful not to view this study as a green light to treat obese or overweight workers differently," cautioned Richard Corenthal, a New York employment attorney.