The drug is used to treat type 2 diabetes, which is linked with poor diet and lack of exercise and accounts for about 90 percent of all worldwide cases.

The new genes do not immediately suggest any new therapy, but may point to a new biological basis for the disease, from which effective treatments could emerge in time.

According to ministers, giving people incentives to fight the flab will help avoid larger costs associated with treating cancer, heart disease and diabetes caused by obesity.