The genes which protect around four million people in the UK from obesity have been discovered following a major research project.

Scientists at Cambridge University say drugs to keep people slim are now a possibility after they identified the handful of genetic factors that prevent overeating.

Medics have known for several years that genes can influence a person’s weight.

However, the new study is significant because it reveals in granular detail which variants suppress or encourage appetite.

The research team analysed the genetic profiles of more than half a million volunteers from the UK Biobank.

They found that around six per cent of British people with European ancestry have a particular combination which means they are more likely to avoid putting on weight regardless of their lifestyle.

Published in the journal Cell, the study focused on a gene known as MC4R which was previously identified by the same Cambridge scientists to play a role in appetite by controlling a receptor in the brain called melanocortin 4.

People who had certain variants of MC4R which disrupted this receptor tended to gain weight easily, the study found, while those who had a different combination caused the receptor to stay “switched on”, enjoying the opposite effect.