A Wellcome Trust-funded English study has led to the identification of a gene, which significantly raises the incidence of obesity in the general population.
Scientists from the Peninsula Medical School in Exeter and the University of Oxford, who conducted the study, say that people with two copies of the FTO gene variant have a 70 per cent higher risk of being obese than those without it.
For their study, the scientists first identified a genetic link to obesity through a genome-wide study of 2,000 people with type 2 diabetes and 3,000 controls, which in turn helped them detect a strong association between an increase in BMI and a variation, or 'allele,' of the gene FTO.
The researchers then tested a further 37,000 samples for this gene from Bristol, Dundee, and Exeter as well as a number of other regions in the UK and Finland.
They found that people carrying one copy of the FTO allele had a 30 per cent increased risk of being obese compared to a person with no copies, while those carrying two copies showed a 70 per cent increased risk, being on average 3 kg heavier than a similar person with no copies.
Published in the journal Science, the study also reports that amongst white Europeans, approximately one in six people carries both copies of the allele.
"As a nation, we are eating more but doing less exercise, and so the average weight is increasing, but within the population some people seem to put on more weight than others," explains Professor Andrew Hattersley from the Peninsula Medical School.
"Our findings suggest a possible answer to someone who might ask 'I eat the same and do as much exercise as my friend next door, so why am I fatter?' There is clearly a component to obesity that is genetic," he adds.
The researchers have, however, yet to unearth why people with copies of the FTO allele have an increased BMI and rates of obesity.
"Even though we have yet to fully understand the role played by the FTO gene in obesity, our findings are a source of great excitement," says Professor Mark McCarthy from the University of Oxford.
"By identifying this genetic link, it should be possible to improve our understanding of why some people are more obese, with all the associated implications such as increased risk of diabetes and heart disease. New scientific insights will hopefully pave the way for us to explore novel ways of treating this condition," he adds.Professor Simon Howell, Chair of Diabetes UK, has welcomed the findings with the hope that they will help tackle rising levels of obesity and type 2 diabetes.
"We welcome this result, which holds promise for tackling rising levels of obesity and the associated risk of developing type 2 diabetes," says Professor Howell.