Australian Study Links Sitting at Work to Obesity in Men

"The current findings present the sedentary workplace as a potentially hostile environment in terms of overweight and obesity," according to authors of the study, reported in the August issue of American Journal of Preventive Medicine.

Lead researcher Kerry Mummery, Ph.D, of Queensland University, and colleagues collected data on 1,579 Australian men and women in full-time jobs. They looked at age, sex, occupation, physical activity, occupational sitting time and body mass index, or BMI, a measure of body fat based on height and weight. People with a BMI of 25 to 29.9 are considered overweight, and 30 or greater, obese.

The researchers found that the workers sat an average of more than 3 hours a day, with 25 percent sedentary at the job more than six hours a day. Men sat an average of 209 minutes on the job, 20 minutes more than women.

Men's twenty extra minutes off their feet appear to make a difference. Statistical analyses showed significant associations between occupational sitting time and a BMI of 25 or above in men but not in women.

"Time and productivity lost due to chronic diseases associated with overweight and obesity may make it financially worthwhile for employers to be more proactive in the health of their employees by promoting physical activity at work," the authors suggest.

Energy imbalance — expending less energy than energy consumed in the form of food — has long been identified as cause of increasing overweight and obesity. In the current study, the authors write, "Higher total daily sitting time was associated with a 68 percent increase in the odds of having a BMI above 25."

Obesity has been identified as a risk factor for numerous chronic diseases including diabetes, coronary heart disease, high blood pressure, stroke and certain forms of cancer. In 2000, the World Health Organization estimated that the number of obese adults worldwide is 300 million. In Australia, there has been a 28 percent increase in overweight and obesity through the 1990s, with 58 percent of men and 42 percent of women currently classified as overweight or obese.

The study researchers did not address why women in general spent less time sitting than men, but noted that professional and white-collar women worker spent significantly more time sitting than blue-collar women.

Mummery WK, et al. Occupational sitting time and overweight and obesity in Australian workers. American Journal of Preventive Medicine 29(2), 2005.