Recent study showed the role played by FTO gene in making a person fat or lean. Research team led by Dr Ulrich Ruther, from the University of Dusseldorf in Germany used animal models to determine how this gene influences weight gain.

Researchers found that this gene affects energy expenditure at the cellular level. Study showed that mice without the FTO gene remained very lean because they spontaneously burn off enormous amounts of energy.

Professor Stephen O'Rahilly, a metabolism expert from Cambridge University, said that genetic variation close to the FTO gene is definitely associated with obesity in humans, but, until now, it was not clear whether this genetic variation was likely to influence obesity by altering the expression or function of the FTO gene itself or some neighbouring gene.

Dr Ruther said: "This finding will promote research into the development of drugs that modulate FTO activity. We strongly suspect that, in man, FTO might have more complex effects on both food intake and energy expenditure than has been so far suggested."