for National Geographic News
Are sedentary obese people intentionally lazy? Not according to a new study, which says some people are natural-born couch potatoes. The study also finds that people who are overweight can take some easy steps to shed pounds.
Researchers at the Mayo Clinic College of Medicine in Rochester, Minnesota, found that obese people with sedentary lifestyles appear to have a genetic inclination to sit around a lot.
The study, to be published tomorrow in the journal Science, investigated the link between inactivity, low energy expenditure, and obesity. The research was part of a program to devise new treatments for obesity, which is fast becoming an epidemic in the United States and other Western nations.
Researchers say there is a factor more important than strenuous exercise in determining who is fat and who is lean. They call it non-exercise activity thermogenesis, or NEAT. The term refers to the calories people burn during everyday activities such as walking, fidgeting, or even just standing.
The study's lead author, James Levine, a Mayo Clinic endocrinologist, said, "Our patients have told us for years that they have low metabolisms. We have never quite understood what that means. The answer is they have low NEAT."
While most people think they must perform physical exercise, such as gym workouts, to burn off excess calories and lose weight, Levine says this isn't the case.
"Our study shows that the calories that people burn in their everyday activitiestheir NEATare far more important in obesity than we previously imagined," he said.
Levine adds that couch potatoes aren't necessarily intentionally lazy. Low NEAT, he says, most likely reflects genetic differences, because his study showed that even after obese people lose weight, they are still inclined to sit for the same amount of time.
Citing the lower obesity rates of 50 years ago, Levine says environmental factors are also at work.
"What has changed in 50 years?" he said. "Not our biology but our environment. This promotes sedentary behaviors."
The study tracked the posture and body position of 20 sedentary volunteers for ten days. This was done via a special undergarment that incorporated technology used in fighter jet control panels. Embedded sensors allowed researchers to monitor even the smallest movements of volunteers every half second, 24 hours a day.
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