Obese are born to put on weight, scientists claim
April 15, 2007
Scientists have discovered the clearest link yet between genes and obesity, in a study that opens the way to explaining why some people seem destined to put on weight while others remain slim.
The researchers have identified a type of genetic variation that gives a child a 70 per cent higher risk of developing obesity compared to a child who has not inherited the genetic variant.
Although the scientists cannot explain how the gene involved makes obesity more likely, they believe the discovery will start a race to find the fundamental reasons why some people are born with a predisposition to being fat.
Professor Andrew Hattersley from the Peninsula Medical School in Exeter said: “As a nation, we are eating more and doing less exercise and so the average weight is increasing but, within the population, some people seem to put on more weight than others,” said
“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’s clearly a component to obesity that is genetic,” Professor Hattersley said.
Obesity is reaching epidemic proportions in the developed world because of the combination of high-calorie food and lack of exercise. In Britain, more than 20 per cent of the population is clinically obese, and half of men and a third of women are classified as overweight.
The study investigated variations in the DNA of a gene known as FTO - short for “fatso” - which occurs in patients with type-2 diabetes. More than 2,000 diabetes patients and 3,000 healthy “controls” took part in the study, published in the journal Science.
The scientists from the Universities of Exeter, Plymouth and Oxford searched the genomes of the diabetes patients and found a strong association between the disease and a certain variant of the FTO gene.
When the scientists expanded the study to look at 37,000 other people without diabetes, they found the same variant was also strongly associated with being overweight. The study found that carrying one copy of the FTO variant imparted a 30 per cent increased risk of obesity compared with a person with no copies.
Meanwhile, having two copies of the same variant increased the risk to 70 per cent - being on average 3kg heavier than a person with no copies of the FTO variant. About one in six white Europeans carry two copies of the FTO variant, according to Professor Mark McCarthy of Oxford University, who took part in the study.
“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,” Professor McCarthy said.
“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,” he said.
Mark Walport, director of the Wellcome Trust, the medical charity that funded the work, said: “Obesity is one of the most challenging problems for public health. The discovery of a gene that influences the development of obesity in the general population provides a new tool for understanding.”
- Source: Obese are born to put on weight, geneticists claim, Independent, Apr. 13, 2007
