Dieters could help themselves to lose weight by thinking about food, according to a new study.
A small-scale study in Science showed that people who had imagined they were eating chocolate wanted it less than those who had not been thinking of it.
The researchers said that imagining eating a favourite food could be a substitute for actually eating it, thereby reducing the desire for it.
A psychologist said this might not work for those with strong cravings.
Researchers at Carnegie Mellon University in Pennsylvania divided 51 people into three groups.
One group imagined eating 30 M&M chocolates, the second group imagined eating three M&Ms, while the third group did not imagine eating any.
When a bowl of the sweets was subsequently presented to the group, those that had thought most about eating the chocolates ate the fewest.
Do you really want it?
The researchers said the study showed that when people thought repeatedly about eating a food, it made them want it less because of a process known as "habituation".
This means that the more that people have of something, the less rewarding it becomes and the less they want of it, even if that feeling is not conscious.
During the tests each group of volunteers had to mentally repeat 33 actions. The actions were either to imagine placing a coin into a laundry machine or eating an M&M - because both involve similar motor actions.
Some participants had to imagine eating more M&Ms while inserting fewer coins, while others did the reverse or only imagined inserting coins.
The study suggested that imagining the experience of eating the chocolates became a substitute for the actual experience and repetition was found to be key to the result.
The co-author of the study, Dr Joachim Vosgerau said that "the difference between imagining and experiencing may be smaller than previously assumed".
Similar results were found when the experiment was repeated using cubes of cheese instead of chocolate.
Professor Andrew Hill, a professor of medical psychology at Leeds School of Medicine described the study as "very interesting" and a novel take on how to stop people craving food.
He explained that most psychological studies look at the "ironic process effect", where people who wish to diet find it very difficult to put unhealthy foods out of their mind.
This, he said, was the opposite psychological effect.
"It's important to look at this process in people who are trying to restrict their intake of these foods. These tend to be people who cannot stop thinking about chocolate, for example. I'm doubtful whether this method would would so well on them."