It may be possible to "think" yourself thin simply by focusing on a recent meal, scientists believe.
A "mind over munchies" study suggests that recalling a previous breakfast, lunch or dinner can suppress the appetite and prevent weight gain.
But simply thinking of food, as opposed to a meal, is not thought to have the same effect. In fact it can make people hungrier, especially if they are dieting.
UK researchers at University of Birmingham asked female students to take part in a bogus biscuit taste test, the real purpose of which was hidden from them.
Just before the test, half the women were encouraged to write a detailed description of a lunch given to them earlier by the researchers. The rest were asked to write an account of their journey to the university campus.
After the taste test the volunteers were invited to eat their fill of the remaining biscuits. Those who had recalled their lunch ate fewer biscuits than those who had recalled their journey.
The effect increased with the amount of time that elapsed between having lunch and eating the biscuits.
Dr Suzanne Higgs, who led the research, told New Scientist magazine the key point of the experiment was that the women were asked to think about a specific meal rather than food in general.
"Other evidence suggests that thinking about food can actually increase subsequent intake, particularly in people who are dieting," she said.
"One possibility is remembering recent eating boosts the influence this information has on decision-making."