Drinking water before meals can help dieters shed extra pounds, according to a new study.

Slimmers can lose an average of 5lb (2.3kg) extra if they drink two cups of water before meals, three times a day.

The study was funded by the charity the Institute for Public Health and Water Research.

While it has long been believed that drinking water can help people feel full, there has been very little scientific evidence to support the claim.

So a team of experts in the US decided to test the theory on 48 adults split into two groups

The first group followed a low calorie diet but did not drink any extra water before meals. Meanwhile, the second group followed the low calorie diet but also drank two cups of water before each meal.

Over the course of 12 weeks, those drinking water lost about 15.5lb (7kg) compared with the non-drinkers, who lost about 11lb (5kg). All adults were aged 55 to 75.

The experts presented their findings at the National Meeting of the American Chemical Society (ACS) in Boston.

Dr Brenda Davy, senior author on the study, said it was the first randomised controlled trial looking at water consumption and dieting.

Dr Davy, from Virginia Tech in Blacksburg, Virginia, said water may be so effective simply because it fills the stomach up with a liquid that has no calories.