Skinny Genes: Why Being Thin Doesn’t Guarantee Great Health

(BlackDoctor.org) — They may be the envy of their fuller-figured friends, but slim people shouldn’t feel too self satisfied.

Why? Because being trim doesn’t guarantee they are healthy.

Researchers have found a so-called ‘lean gene’ that helps them keep weight off but also raises their odds of developing diabetes and heart disease.

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Scientists compared the genetic codes of more than 75,000 people with the ratio of fat to muscle in their bodies. This revealed an extremely common gene called IRS1 to be linked to leanness. But while we are used to hearing about the many health benefits of being thin, IRS1 seemed to buck the trend.

Those with the gene had higher levels of dangerous blood fats and found it harder to process sugar. This put them at a 20 per cent higher risk of developing heart disease and type 2 diabetes – the form that develops in middle-age and is often blamed on obesity. As the gene is only linked to lower levels of fat stored just below the skin, known as subcutaneous fat, it may be that people who have IRS1 stash theirs elsewhere. If fat is wrapped around the heart, liver or other organs it could lead to life-threatening conditions.

The study, reported in the journal Nature Genetics, involved teams at 72 institutions in ten countries. People, particularly men, with a specific form of the gene are more likely to be lean and to develop heart disease and type 2 diabetes.

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In simple terms, it is not only overweight individuals who can be predisposed for these diseases, and lean individuals shouldn’t make assumptions that they are healthy based on their appearance.

The effects may be more pronounced in men because they store less fat than women, and could be more sensitive to changes in its distribution. More research will provide new insights into why not all lean people are healthy and, conversely, why not all overweight people are at risk of metabolic diseases.

But 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.