Donna M. Gates of the University of Cincinnati and colleagues measured various aspects of productivity in a random sample of 341 manufacturing employees.

Most of the workers were overweight or obese -- 23 percent were mildly obese with a body mass index of 30 to 34.9, 13 percent were moderate to extreme obese -- BMI of 35 or higher and 43 percent were classified as overweight but not obese -- BMI 25 to 29.9.

Workers with moderate to extreme obesity had the greatest health-related limitations at work.

The study, published in the Journal of Occupational and Environmental Medicine, found that the moderately to extremely obese workers had limitations in time needed to complete work tasks and ability to meet physical work demands. These limitations were significantly greater than in the overweight or mildly obese groups, Gates said.