THURSDAY, May 26 (HealthDay News) -- As Americans sit -- literally -- in more sedentary jobs, they're packing on the pounds, and it's this inertia that's a major contributor to the obesity epidemic, new research suggests.
Staring at the computer for hours rather than hoeing the fields means Americans are burning 120 to 140 fewer calories a day than they did 50 years ago.
So promoting any kind of physical activity needs to have an even greater emphasis in this war on weight, according to a study in the May 25 online edition of the journal PLoS ONE.
"It's all about calories in and calories out, and we're putting more calories in than we're taking out," said Dr. Robert Graham, a primary care physician at Lenox Hill Hospital in New York City.
A tilt towards calories in has resulted in two-thirds of U.S. adults now being overweight or obese.
Although both eating habits and exercise have been studied in relation to the obesity epidemic, these researchers, from the Pennington Biomedical Research Center in Baton Rouge, La., said much of the blame for the extra poundage has been placed on calorie intake.
That's because the amount of leisure-time physical activity hasn't really changed over the years.
But what about the physical demands of work, where so many people spend most of their waking hours?
These researchers cross-referenced U.S. Bureau of Labor Statistics on the prevalence of different jobs with a large national database that includes information on body weight.
Fifty years ago, about half of private-industry jobs in the United States involved some kind of physical activity, things such as farming, mining, construction and manufacturing. Today, that number is less than 20 percent, thanks to the dominance of jobs in retail, education and business.
The authors estimated that 100 fewer calories going out every day would result in a weight gain in line with what the U.S. population has seen since 1960.
Yet, if Americans were following federal guidelines for physical activity (150 minutes a week of moderate-intensity exercise or 75 minutes of more vigorous activity), those extra calories would have been evened out.
Only one in four Americans is doing the recommended level of exercise, the authors stated.
"We need to encourage physical activity even more, especially given that we sit more during the day than we did 100 years ago," said Keri Gans, a spokeswoman for the American Dietetic Association and author of The Small Change Diet.
"The demands of everyday life are competing with exercise," Graham added. "We just have to make time for it."
Gans recommends that people move at work even if they have what amounts to a desk job. That could mean taking the stairs when you can, walking over to a co-worker's desk when you can and going for a walk at lunchtime. And if your company happens to have a gym or exercise program, by all means, partake.
The U.S. Centers for Disease Control and Prevention has more on how to get moving.
SOURCES: Keri M. Gans, R.D., spokeswoman, American Dietetic Association, and author, The Small Change Diet; Robert Graham, M.D., primary care physician, Lenox Hill Hospital, New York City; May 25, 2011, PLoS ONE, online
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