Now women can drop two dress sizes and that too in a year as a double diet drug has been developed.

Orlistat, the drug that most GPs prescribe for obesity, will now be overtaken by the pill, which is a combination of two existing drugs, and it is stated that thie combination has more than twice the slimming power of orlistat.

Reports state that there is a reduction in blood pressure with Qnexa and also the level of blood fats and sugars go down with this drug.

The safety of the drug is however a matter of concern as before the drug is approved for sale; more data has to be produced for which manufacturers are being told.

In the 1990s, Duchess of York was helped in losing three stones by phentermine, the amphetamine-based slimming drug, and Qnexa is a combination of this and topiramate, an epilepsy drug linked to weight loss.

Almost 2,500 overweight and obese Americans were given Qnexa once a day for a year or a ‘dummy’ placebo pill.

The NHS at the moment has only orlistat to fight obesity and a weight loss of about over a stone and a half was experienced by those taking the highest doses.

The scientists, led by Dr Kishore Gadde, from Duke University Medical Centre in North Carolina, said, “The combination of phentermine and topiramate, with lifestyle interventions, might be a valuable treatment for obesity.”