Having a leaner body may not always mean you have a lower risk of heart disease, according to a new study.

Researchers have identified a gene that lowers the amount of fat stored under your skin, but does not lower the amount of 'unseen' fat around your internal organs.

They also found people with the gene had unhealthy levels of cholesterol and glucose in their blood, which are risk factors for diseases such as heart disease and type 2 diabetes.

Professor Jeremy Pearson, associate medical director at the British Heart Foundation, said: "These results reinforce the idea that it is not just how fat you are, but where you lay down fat that's particularly important for heart risk. Fat stored internally is worse for you than fat stored under the skin.

"The results help us to understand why some slim people become insulin resistant, which is the first stage of type 2 diabetes, and may lead to better targeted use of medicines to prevent insulin resistance in future.

"However, they don't detract from the fact that being overweight is bad for your heart health, so we should still try to stay lean and fit."

Notes:

The study is published in Nature Genetics.

Statement issued in response to study: "Genetic variation near IRS1 associates with reduced adiposity and an impaired metabolic profile" by T. Kilpeläinen, M Zillikens, A Stančáková, R Loos et al. will appear in the July 2011 issue of Nature Genetics. Doi:10.1038/ng.866

Source:
British Heart Foundation