Lean men can still have too much belly fat

BOSTON, June 28 (UPI) -- Lean people with a specific gene, especially men, are at increased risk for lower body fat, heart disease and type 2 diabetes, U.S. researchers found.

Dr. Douglas P. Kiel and David Karasik, both of the Institute for Aging Research of Hebrew SeniorLife, an affiliate of Harvard Medical School, working with the Framingham Heart Study, identified a gene linked with having less body fat, but also with an increased risk of type 2 diabetes and heart disease.

"We've uncovered a truly fascinating genetic story and, when we found the effect of this gene, we were very intrigued by the unexpected finding," Kiel says in a statement. "People, particularly men, with a specific form of the gene are both more likely to have lower percent body fat, but also to develop heart disease and type 2 diabetes. In simple terms, it is not only overweight individuals who can be predisposed for these metabolic diseases."

The researchers examined the genomes of more than 75,000 people and found strong evidence the gene IRS1 linked having less body fat, but unhealthy levels of cholesterol and blood glucose.

The study, published in the journal Nature Genetics, found the gene lowers only the "subcutaneous" fat under the skin, but not the more harmful "visceral" fat that surrounds organs, where it can hurt organ function.