Tuesday, August 5, 2008

Is ‘laziness gene’ to blame for couch potatoes?

If you always have a hard time motivating yourself to exercise, could a “laziness gene” be partly to blame?

That just might be the case, according to scientists from the University of North Carolina in Charlotte. Their recent studies with mice could help explain the origins of a lack of desire to get up and get moving.

Researchers found a cluster of about 20 genes that appear to determine which mice tended to be active and which tended to be inactive. And boy, were the active mice active: They ran five to eight miles a day on their little exercise wheels — quite a feat, considering the size of a mouse’s tiny gait.

In contrast, the “inactive” mice ran just 0.3 miles a day. And that’s not all.

“The mice that were inactive put wood shavings in their treadmills and made them beds — or actually used them as potties, which tells you what they think of exercise,” Time Magazine Science Editor Jeffrey Kluger told TODAY co-host Natalie Morales on Tuesday.

Time.com reported on the scientists’ findings, which were published in the Journal of Heredity. During his TODAY Show interview, Kluger stressed that mice are “good but imperfect templates for human beings.” The so-called laziness gene has not yet been found in humans, although the University of North Carolina researchers are preparing to conduct a similar study in men and women.

Doomed to inactivity?
Madelyn Fernstrom, director of the University of Pittsburgh Medical Center’s Weight Management Center, told TODAY that even if some humans are found to have a genetic predisposition toward laziness, that’s not the end of the story for them.

“You’re not doomed to be a couch potato even if you do have a biological tendency,” Fernstrom said. “You just have to work a little harder.”

Fernstrom advised people who feel hard-wired toward sloth to increase their “activity of daily living.”

“Take more steps, walk up an escalator, park further away, lose the remote control, walk around while you’re talking on the phone,” she said.

She also recommended that exercise-avoiders should find forms of exercise they actually enjoy and work out with an exercise buddy in order to stay motivated.

“Don’t use an excuse saying, ‘Oh, it’s my genes (that) made me do it,’” Fernstrom said. “That is absolutely not true!”

Kluger noted that any inherent drive toward activity or inactivity likely is tied to levels of neurotransmitters in the brain — particularly serotonin and dopamine.

“The thinking is this probably triggers serotonin and dopamine in the brain, which are mood elevators or mood determinants,” Kluger said.

“Remember, people who are clinically depressed tend to be very inactive. People who aren’t clinically depressed tend to be more active. And when you are active, you actually do elevate your mood and you do actually change the level of serotonin and dopamine in your brain. So it’s clear that the brain system and a sense of activity and energy are linked.”

Connection to the ‘exercise pill’
What about another recent headline-grabbing study involving mice who seemed to benefit from taking a so-called “exercise pill”? Researchers at the Salk Institute for Biological Studies found that when the drug in question was given to sedentary mice, their cells’ ability to burn fat and retain muscle mass improved.

If humans are someday found to have a genetic predisposition toward physical inactivity, could such a drug be a possible answer for them?

In short, no, Kluger said.

“There are so many other benefits that come from exercise,” Kluger said. “There’s mood elevation, there’s reduction of osteoporosis, there’s reduction of diabetes, there’s cardiopulmonary benefits. You get none of this (with a pill). So we’d be slender, unhealthy people, as opposed to slender, healthy people.”