Those without FTO gene stay slim without dieting or added exercise, German researchers say
SUNDAY, Feb. 22 (HealthDay News) -- Mice without a particular form of an obesity-linked gene are thinner than mice carrying the gene, even though they exercise similarly and gobble up just as much food.
So conclude German investigators, who reported the finding in the Feb. 22 issue of Nature. According to the team, this is the first time that scientists have been able to explain how an obesity-linked gene -- in this case the FTO gene -- may predispose a person to be either skinny or obese.
"These animals are eating as much as the control animals but burning calories through a non-exercise mediated pathway," said one expert, Dr. Stuart Weiss, a clinical assistant professor of medicine at New York University School of Medicine in New York City.
Previous research had determined that having the "fat" variant of the FTO gene can add as much as 3 kilograms (6.6 pounds) to a person's heft.
In the current study, "the gene was knocked out, so there was no product of the gene in the body," explained another expert, Weimin He, an assistant professor at Texas A&M Health Science Center's Institute of Biosciences and Technology in Houston.
Mice lacking the FTO gene displayed slowed growth after birth (though not before) and less fat tissue. And by the age of 6 weeks, these mice had 30 percent to 40 percent less weight than their "normal" counterparts. Lean mass was also lower, but to a lesser extent.
So how did the FTO-less rodents stay so svelte, despite similar diet and exercise? "The study authors say it's because of increased energy expenditure," He said. "Now the question is, why?"
The German team, led by Ulrich Ruther of the University of Dusseldorf, investigated further to try and find an answer.
Blood levels of the hormone leptin, which helps control appetite and the ba
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