New research has revealed why some people with obesity remain relatively healthy while others suffer from life-changing conditions such as strokes and heart disease.
Our genes determine where and how fat is stored, which is known as having ‘favourable’ or ‘unfavourable’ adiposity.
Anyone with a BMI over 30 is considered obese, but two people with the same BMI can have very different levels of fat stored in different places and ways.
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. 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.”
Using a technique called Mendelian randomisation, researchers analysed data from Finland’s FinnGen project and the UK Biobank, which contains information from 500,000 individuals aged 37 to 73 between 2006 and 2010.
Of the 37 diseases scientists tested for, 12, including strokes and coronary artery disease, were directly linked to the genes that determine a ‘favourable adiposity.’
Meanwhile, nine were unrelated to adiposity and were more likely due to an individual carrying too much weight, such as deep vein thrombosis.
The researchers also discovered that some diseases previously thought to be linked to body weight, such as Alzheimer’s, appear to be unconnected.
“To better prevent and measure risk of disease, it is important to understand if obesity is a casual risk factor and if it is causal, which consequences of it – be they metabolic, mechanical or psychological – are deriving the risk,” said Dr Yaghootkar.
She added: “Our results also provide evidence that everyone will benefit from losing their extra fat even if they are metabolically healthy.”
The researchers said that the findings will help doctors decide whether to focus on targeting the adverse effect’s of a person’s obesity or encourage them to lose weight.
“For example, there are many treatments that can lower the high-fat levels in the blood and around the organs that do not affect the extra weight a person carries,” said Prof Timothy Frayling, Professor of Human Genetics at the University of Exeter.
“In contrast, for other conditions, it may be more important to reduce the extra weight as much as, or more than, the damaging high sugar and fat levels in the blood.”
