Just imagining eating calorific food such as chocolate can reduce your appetite and help you lose weight, claim psychologists

Ever wished you could cut down on the amount you eat without going hungry? It turns out all you need is a good imagination. Scientists have found that going through the mental motions of eating, say, a chocolate bar, will help.

The result, from a study of more than 300 volunteers, seems to fly in the face of intuition that imagining a delicious meal will make your mouth water even more.

Carey Morewedge, an assistant professor of social and decision sciences at Carnegie Mellon University in Pennsylvania, and the lead author of the research, which is published in Science, said: "We think our results may be used to craft behavioural interventions that allow people to eat less of the unhealthy foods they crave and also to choose healthier foods.

"We hope it can also be used to give us [help] on cravings for other substances including cigarettes and alcohol."

He said: "Trying to suppress one's thoughts of desired foods in order to curb cravings for those foods is a fundamentally flawed strategy.

"Our studies found that people who repeatedly imagined the consumption of a morsel of food — such as an M&M or cube of cheese — subsequently consumed less of that food than people who imagined consuming the food a few times or performed a different task."

Some of the volunteers were asked to imagine eating either three or 30 chocolate M&Ms, or small cubes of cheddar cheese. Others imagined carrying out various actions such as eating a different food or moving the M&Ms or cheese cubes around rather than eating them.

After that, each participant was given a bowl filled with M&Ms or cheese cubes and asked to rate the food for a taste test.

Morewedge and his team saw a reduction of around 50% in the amount of food consumed by participants who had been told to imagine eating before being given the bowl of food,.

He said: "These are not huge differences in absolute numbers – people would tend to eat 2g rather than 4g of M&Ms, which is two or three versus five M&Ms. Or 6g of cheese instead of 11g."

Morewedge said: "We have two components in our desire for food: liking and wanting. You may very much like ice cream but not want it for breakfast. We also have a more motivational aspect called wanting, and that's more of a desire to consume this thing right now or to obtain more of it.

"What this seems to be doing is affecting our wanting drive to consume the food, rather than how good we think it is."

Joachim Vosgerau, assistant professor of marketing at Carnegie Mellon University, said that the research examined "habituation", a neurological process that determines how much we consume of a food or a product, when to stop consuming it, and when to switch to consuming something else.

He said: "Our findings show that habituation is not only governed by the sensory inputs of sight, smell, sound and touch, but also by how the consumption experience is mentally represented.

To some extent, merely imagining an experience is a substitute for actual experience. The difference between imagining and experiencing may be smaller than previously assumed."

This habituation, added Morewedge, tends to occur more quickly than the other direct messages that are used to tell us when to stop eating, such as the direct messages from our digestive systems to our brains.