Scientists from Oxford and Cambridge say in their second discovery they have found new genetic variants that influence fat mass, weight and risk of obesity and increase the chances of being fat, which may explain why some people are always battling with their weight.
A team from Oxford's Genetics of Energy Metabolism (GEM) consortium and Oxford University have picked up a stretch of rogue DNA that is carried by more than a third of the population and increases the chances of becoming fat.
The research involved 77 institutions in six countries which analysed the DNA of 90,000 individuals from the UK, USA, France, Germany, Italy, Finland and Sweden.
It revealed that the effects of the rogue DNA are exacerbated by the presence of the FTO gene, discovered last year, which was the first widespread gene known to affect obesity.
They believe their discovery could explain why some people seem to effortlessly lose weight while others have a constant battle.
The researchers say it is important people understand there is a genetic predisposition to obesity and as genetic sequences come in pairs, the effect is greatest in those with two flawed copies.
They say this may help people adopt a less prejudicial attitude towards the obese.
The scientists say unraveling the genetics of obesity could also lead to treatments for the condition; around 37 per cent carry one copy and are 12 per cent more likely to be obese.
Those with two copies of the newly-discovered DNA and two flawed copies of FTO are often more than half a stone heavier than those without such an inheritance.