Washington: Jealous of your friend who hardly gains weight even though gorging on junk food always? Well, your friend may be blessed with a special hormone called orexin, scientists say.
Researchers at the Sanford-Burnham Research Institute in Orlando, the US, found a strong link between orexin, which is produced in the brain, and the calorie-burning ability of brown fat in mice -- a finding they believe could hold true for humans.
Though the new findings are preliminary, the researchers suggested that supplementing this metabolism-stimulating hormone could be a way to help people lose weight, LiveScience reported.
In the study, the researchers compared normal mice with mice engineered to lack orexin. When fed a high-fat diet for six weeks, the orexin-deficient mice increased their body weight by 45 per cent, while the normal mice plumped up by just 15 per cent.
This increased weight gain happened even though the orexin-deficient mice ate less of their food than the normal mice did, the researchers found.
The hormone, they said, helps stave off weight gain as it`s involved in the body`s production of brown fat, which burns calories rather than storing them as white fat does.
"Without orexin, mice are permanently programmed to be obese. With it, brown fat is activated and they burn more calories," said study researcher Devanjan Sikder.
"Our study provides a possible reason why some people are overweight or obese despite the fact that they don`t overeat," Sikder said.
According to the researchers, who detailed their findings in the journal Cell Metabolism, orexin deficiency is known to exist in people with narcolepsy, and previous studies have linked low levels of orexin and obesity in people.
Measuring the activity of brown fat in people with orexin deficiencies could show whether the same mechanism is at work in people, they said.