Obesity becomes more than just a personal health issue when it affects job performance, and a new study from Statistics Canada says it's doing just that for many Canadians.

More Canadian workers are now obese, the agency says, with the rate of Obesity rising from 12.5 per cent in the mid-1990s to 15.7 per cent in 2005. Obesity is most prevalent among older workers aged 55 to 64, 21 per cent of whom were obese in 2005.

Many of those workers are finding it harder to get their job done, with some needing to cut back on their activities, some getting injured and others needing to take more days off.

The odds of being absent from work are almost four times higher for obese young men than for those with normal weight, the agency reports. Obesity is also related to reduced work activities and more disability days for women aged 35 to 54.

It can also mean an increased likelihood of getting hurt on the job. Obese workers often have problems with fatigue and physical limitations, which can result in an injury. They may not wear personal protective equipment, such as gloves and goggles, because they don't fit or are uncomfortable to wear. And, they tend to take more medications for chronic conditions, which might also increase the risk of injury.

Older obese women were significantly more likely to have reported a work injury during the past year than those with body weight in a normal range. The researchers say this is consistent with previous research that found that obese women are significantly more likely to be injured at work than those in the normal weight range.

Obese workers also have higher job strain, which is defined as high psychological demands combined with low job control. Many also felt they received low social support from colleagues and supervisors at work.

For many, obesity isn't just causing problems with their work; their work might actually be causing their obesity.

Shift work and excessive hours are associated with obesity, the StatsCan study finds, and a higher proportion of blue-collar workers are obese compared with men in white-collar jobs.

"The increasing trend of obesity among workers may be attributable to an environment that, in multiple ways, encourages excessive eating and discourages physical activity and to increases in more sedentary jobs," the study authors say.

Interestingly, while low-income seemed to translate into higher rates of obesity for women, income had the opposite effect on men, with high personal income linked to obesity. The researchers say that may be because higher-income men tend to dine out more often, which may lead to weight problems, as recent research has suggested.

Low education significantly increases the odds of obesity for both men and women, (except for young workers aged 18 to 34). For example, workers aged 35 to 54 with less than a high school education were 1.6 times more likely to be obese than workers who had completed postsecondary education.

The study authors says that reducing or preventing obesity in the workplace would have many benefits, including better health and wellbeing of workers, as well as the potential for higher productivity and better job performance.

"It may be cost-effective for employers to actively sponsor health promotion initiatives in the workplace, including weight maintenance program," they write.