Fidgeters have advantage in weight loss, study finds

February 3, 2005

By Lee Bowman

We all know them, those frustratingly lean machines who eat as much or more fattening stuff than we do, never deliberately exercise, and yet don't put on the pounds.

Now, an elaborate new study by researchers at the Mayo Clinic helps explain, at least in part, how the metabolisms of seemingly identical couch potatoes with the same lifestyles can be so different.

It turns out that obese couch potatoes sit still, on average, 150 minutes more each day than lean couch potatoes, who despite equally sedentary jobs and non-existent exercise habits, manage to walk, play, fidget and generally move around enough each day to burn about 350 calories more than the obese couch denizens do.

The researchers, who report their findings Friday in the journal Science, call this phenomena "non-exercise activity thermogenesis" (NEAT for short) and have spent nearly a decade designing the instruments and techniques to capture a person's every move.

"Our patients have told us for years that they have low metabolism, and as caregivers, we have never quite understood what that means, until today," said Dr. James Levine, an endocrinologist at the Rochester, Minn., clinic and lead author of the study.

"The answer is that they have low NEAT, which means they have a biological need to sit more. A person can expend calories either by going to the gym, or through everyday activities. Our study shows that the calories that people burn in their everyday activities are far, far more important in obesity than we previously imagined."

Other research that has measured calorie burn through respiration has also pointed toward the effect of incidental exercise. And despite the much-maligned supersizing of modern diets, many studies have shown that an inactive lifestyle is at least as important in getting fat.

"The difference in NEAT observed between obese and lean individuals is significant and implies that obesity might be prevented and treated through simply limiting sedentary activities or increasing behaviors such as standing, walking and fidgeting," said Eric Ravussin, an obesity researcher at the Pennington Biomedical Research Center in Baton Rouge, La., in an article appearing in the same issue of Science.

Levine's team laid the groundwork for the current study with another Science report six years ago, when they noted that a group of equally overfed volunteers gained different amounts of weight and suggested that the difference was explained by individual differences in how they expended energy outside formal exercise.

The next step was to come up with a way to measure the energy used by every toe tap and calculate the calorie burn differences. Central to the effort was the Physical Activity Monitoring System (PAMS), a movement-monitoring system that borrows technology from fighter-jet control panels.

Movement sensors were embedded in specially designed underwear worn by 20 volunteers 24 hours a day _ minus a 15-minute-a-day shower and underwear change break that was counted as "standing."

The sensors tracked the body postures and movements of 10 lean and 10 obese sedentary persons as they went about their ordinary routines at work and home every half-second, with the data dumped each day from a recorder pack worn at the waist. There were just two restrictions on the volunteers _ they had to eat only what the researchers prepared and take meals at the hospital, and they weren't allowed to swim, since the sensors aren't waterproof.

Levine conceded that the instrument package "appears slightly bizarre as it gives us a covert window into people's energetics and every activity in a completely unthreatening way. But because of it, we have a window into people's activity life that no one's ever had before"

In the second phase of the study, volunteers kept to the same routines while the researchers overfed the lean group by 1,000 calories a day and underfed the obese by 1,000 calories a day, then monitored them for another 10 days. Although they lost weight on the diet, the naturally obese group sat more and moved less; the lean team gained weight from the extra calories, but still moved more than the others.

The Mayo researchers argue that promoting a revolution of fidgeting might be one way to reverse the obesity epidemic. "Unlike running a marathon, NEAT is within reach of everyone," Levine said.

Source:www.rocklintoday.com