People tend to take more generous helpings when the food they eat is of the same hue as the crockery on which it is placed, says a new study.
When foods "blend in" with their background, people serve themselves 20 percent more than if they were serving the same meal on a plate of contrasting colour.
In the study, people were given either a red or a white dinner plate and led to one of two buffet tables offering pasta; one in tomato sauce, the other in cream sauce, the Telegraph reports.
Those given crockery which "matched" their food - red for tomato sauce, or white for cream sauce - gave themselves helpings between 17 and 22 percent larger than those with plates of contrasting colour.
Further, research has established that the average person eats around 92 percent of a portion they serve themselves.
The latest study by researchers at Cornell University, US, repeated several times on groups of 60 participants, found the actual colour of the food and plates made no difference; what mattered was the contrast between the two.
Study authors said the colour contrast appears to act as a "stop sign" reminding people to think about how much food they were serving.
Brian Wansink, professor who runs Cornell University's Food and Brand Lab, said: "People will generally serve themselves far more on a large dinner plate than they would on a smaller one, because the eye is tricked. It seems that colour contrast is one way to block this illusion."
The research author said those trying to lose weight could help themselves by buying brightly coloured or dark plates, to provide contrast with common white foodstuffs such as pasta, rice and potatoes.
Alternatively, green plates could be used as a way to trick children into eating more vegetables, he said.