Drinking water before meals can help people to lose weight, says a US study.
Scientists from Virginia found that slimmers can lose an average of 5lb extra if they drink two glasses of water three times a day before meals.
They tested the theory on 48 older adults, split into two groups, over 12 weeks.
While drinking water can make you feel full on zero calories, say researchers, too much water can also lead to serious health problems.
The researchers presented their findings at the National Meeting of the American Chemical Society in Boston.
All adults who took part in the study were aged 55 to 75.
The first group followed a low-calorie diet but did not drink any extra water before meals.
The second group followed the low-calorie diet but also drank two glasses of water before each meal.
Over the course of 12 weeks, those drinking water lost about 15.5lbs while the others lost about 11lbs.
A previous study found that middle-aged and older people who drank two glasses of water before eating a meal ate between 75 and 90 fewer calories during that meal.
Professor Brenda Davy, senior author of the study, from Virginia Tech, said it was the first randomised controlled trial looking at water consumption and dieting.
She said the reason water may be so effective is because it fills up the stomach with a liquid that has no calories.
"People should drink more water and less sugary, high-calorie drinks. It's a simple way to facilitate weight management," Professor Davy said.
Diet drinks and other drinks with artificial sweeteners may also help people reduce their calorie intake and lose weight, researchers said.
However, Professor Davy advised against drinks sweetened with sugar, because they are high in calories.
A regular can of fizzy drink contains about 10 teaspoons of sugar, she explained.
The study was funded by the charity, The Institute for Public Health and Water Research.