A middle-aged spread may be a sign a person has “lucky” genes which protect against some diseases, according to a new study.
The genes control how a person’s body distributes its fat with some people storing ‘visceral fat’ predominantly around their vital organs.
Others meanwhile have so-called “favourable” genes that prevent this and see fat stashed away from the organs and in less harmful locations, like as a paunch or double chin.
Scientists say the findings explain why some obese people (with a BMI above 30) remain relatively healthy, while others suffer from debilitating conditions like type 2 diabetes and heart disease.
Dr Hanieh Yaghootkar, a lecturer in biosciences at Brunel University London, who led the research, said: “Some people have unlucky fat genes, meaning they store higher levels of fat everywhere including under the skin, liver and pancreas.
Obesity not to be taken lightly
“That’s associated with a higher risk of diseases such as type 2 diabetes.
“Others are luckier and have genes that mean higher fat under the skin but lower liver fat and a lower risk of diseases like type 2 diabetes.”
In the study, published in the journal eLife and funded by Diabetes UK, researchers looked at 37 diseases thought to be linked to obesity. Twenty-one of these were found to have a causal link, where a BMI of at least 30 is a direct trigger of the disease.
Twelve of the 21 – including coronary artery disease, stroke and type 2 diabetes – were more specifically linked to these lucky genes which determine how and where the fat is stored.
The other nine conditions were linked to obesity, but not the lucky genes. Instead, they are simply caused by a person weighing too much and putting added strain on their body. Deep vein thrombosis and arthritic knees are examples of this.
But the researchers warn that even if a person is, by pure chance, in possession of these fortuitous genes, they would be in better health and less at risk of chronic disease if they were not obese.
Dr Yaghootkar said: “To better prevent and measure risk of disease, it is important to understand if obesity is a causal risk factor and, if it is causal, which consequences of it – be they metabolic, mechanical or psychological – are deriving the risk.
“Our results also provide evidence that everyone will benefit from losing their extra fat even if they are metabolically healthy.”