Rise of obesity - risks at work

By Dr. Ananya Mandal, MDMay 29 2011

A team of researchers have found that the American workplace is a significant contributor to the obesity epidemic. In the review of shifts in the labor force since 1960 it was suggested that a sizable portion of the national weight gain can be explained by declining physical activity during the workday.

Jobs requiring moderate physical activity, which accounted for 50 percent of the labor market in 1960, have plummeted to just 20 percent the researchers found. The remaining 80 percent of jobs, the researchers report, are sedentary or require only light activity. The shift translates to an average decline of 120 to 140 calories a day in physical activity, closely matching the nation’s steady weight gain over the past five decades, according to the report, published Wednesday in the journal PLoS One. The study found that in 1960, one out of two Americans had a job that was physically active. Now it is estimated that only one in five Americans achieves a relatively high level of physical activity at work.

At present one third of the Americans are obese. Researchers caution that workplace physical activity most likely accounts for only one piece of the obesity puzzle, and that diet, lifestyle and genetics all play important roles. However this new study suggests that health care professionals and others on the front lines against obesity, who for years have focused primarily on eating habits and physical activity at home and during leisure time, have missed a key contributor to America’s weight problem. The findings also put urge employers to increase workplace heath initiatives and pay more attention to physical activity at work.

Dr. Timothy S. Church, a noted exercise researcher at the Pennington Biomedical Research Center in Baton Rouge, La., and the study’s lead author said, “If we’re going to try to get to the root of what’s causing the obesity epidemic, work-related physical activity needs to be in the discussion… There are a lot of people who say it’s all about food. But the work environment has changed so much we have to rethink how we’re going to attack this problem.”

Dr. Church notes that because the research does not factor in technological changes, like increasing reliance on the Internet and e-mail, many people in service and desk jobs that have always involved only light activity are now moving less than ever, meaning the findings probably understate how much physical activity has been lost during work hours.

Dr. Church said that during an analysis on the country’s obesity patterns, he was surprised by the fact that Mississippi and Wisconsin both had high rates of obesity, despite having little in common in terms of demographics, education or even weather. It occurred to him that both states had waning agricultural economies, prompting him to begin exploring the link between changes in the labor force and declines in workplace physical activity.

He quickly discovered that a decline in farming jobs alone could not explain increasing obesity around the country, and began exploring job shifts over several decades. Using computer models, Dr. Church and colleagues assigned metabolic equivalent values to various job categories and then calculated changes in caloric expenditure at work from 1960 to 2008.

Barbara E. Ainsworth, the president-elect of the American College of Sports Medicine and an exercise researcher at Arizona State University said, “It’s a light bulb, ‘aha’ moment… I think occupational activity is part of that missing puzzle that is so difficult to measure, and is probably contributing to the inactivity and creeping obesity that we’re seeing over time.” “The activity we get at work has to be intentional,” Dr. Ainsworth said. “When people think of obesity they always think of food first, and that’s one side of it, but it’s high time to look at the amount of time we spend inactive at work,” she said.

Ross C. Brownson, an epidemiologist at Washington University in St. Louis said, “We need to think about physical activity as a more robust concept than just recreational physical activity.” “In many ways we’ve engineered physical activity out of our lives, so we’ve got to find ways to put it back into our lives, like taking walks during breaks or having opportunities for activity that are more routine to our daily lives, not just going to the health club.”