Skip to navigation | Skip to content

Fidgeting fights flab

lean genes?

Brain chemicals that make you restless and fidgety may also play a role in keeping you lean, a researcher believes (Image: iStockphoto)

Thin people's brains may be more sensitive to a naturally occurring chemical that makes them wriggle, jiggle and fidget through the day, an international obesity conference will hear.

US researcher Associate Professor Catherine Kotz from the Minneapolis Veterans Affairs Medical Center and the University of Minnesota will present her research on the neuropeptide, orexin-A, at an international obesity conference in Sydney this week.

Previous research has shown that orexin-A, which was only discovered in the last decade, makes us burn energy by stimulating unconscious activity like fidgeting and restlessness.

Kotz says her study, published online in the American Journal of Physiology, shows orexin-A affects activity in rats when injected into their brains.

"We injected orexin-A into normal rats and it caused increased movement," she says.

"When we inject it into lean rats they're very sensitive to it; they really increase their movement. The obese rats don't seem to respond.

"So that said to us there is some difference in the orexin-A signalling in their brains."

Underpants study

Kotz's research grew out of an earlier study by Dr James Levine of the Mayo Clinic.

In his study Levine put lean and fat people into underwear with built-in sensors that gauged their movement through the day.

That research, published in the journal Science last year, found that lean people spend an average two hours more a day than their obese counterparts doing unconscious, spontaneous movements such as lifting their arms, jigging a foot or getting up and down.

"What he found ... is that lean individuals move for two hours more per day than obese individuals," she says.

"This is activity that was not going to the gym, not exercising."

The fidgeters burnt about 350 kilocalories a day through this non-specific movement, the equivalent of a 45 minute brisk walk.

Orexin-A on the brain

When Kotz's team did brain scans on their orexin-A enhanced rats, they found that the lean rats had about double the number of orexin-A receptors than the obese rats, suggesting it's sensitivity, rather than quantity, that counts.

The difference in receptor number could be because of genetic programming or changes produced by over or under stimulation during life, she says.

This question is the subject of further study.

Kotz says while the rat study hasn't been done in humans, our brains also produce orexin-A.

She says her findings could eventually lead to an anti-obesity treatment, such as a patch, that either increased the number of brain's orexin-A receptors or boost the sensitivity of existing ones.

Tags: health, science-and-technology, neuroscience