Eat to lose weight

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 you eat less of the real stuff immediately afterwards. The result, from a study of 300 volunteers, seems to fly in the face of intuition that imagining a delicious meal will only make your mouth water even more. The researchers hope the results can be used to devise strategies that help people control their appetite and weight. "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." said Carey Morewedge, an assistant professor of social and decision sciences at Carnegie Mellon University in Pennsylvania, US.

More than 300 volunteers were told they were going to participate in a study looking at how imagination affects perception. Some were asked to imagine repeatedly eating either 3 or 30 chocolate M&Ms, or small cubes of cheddar cheese. Others imagined carrying out various actions such as eating a different food altogether 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 eat some so that they could rate the food for a taste test. Once they had finished, the experimenter secrety removed the bowl to be weighed. 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, compared with those participants who were just told to picture the food or imagine something else entirely.

"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 of cheese." The researchers think that the imagination part of the experiment reduces how much we want to eat the food.

  • We have two components in our desire for food: liking and wanting. You may very much like ice cream but not want to eat it for breakfast.
  • We have some idea of how pleasurable it is to eat a particular kind of food or how much you prefer it to other kinds of food.
  • 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 in general." 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.

"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.