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.