Want to Eat Less? Imagine Eating More

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Imagine you could eat less, simply by thinking about eating! A new study published in Science finds just that: people who imagined themselves repeatedly indulging in sweet or salty treats ended up eating less of the actual foods than people who didn’t visualize eating the same foods or thought about them only fleetingly.

The study is based on the principle of habituation — that repeated exposure to a stimulus reduces people’s response to it. It explains why the 10th bite of pumpkin pie isn’t as desirable as the first. And why chronic alcoholics need more alcohol to feel drunk. “People habituate to a wide range of stimuli, from the brightness of a light to their income,” the study’s authors write. (More on Time.com: 5 Ways to Get Oatmeal in Your Diet, Deliciously)

What the authors wondered, however, is why, when it comes to food, does the imagination usually have the opposite effect — the mere notion of a piece of pie tends to whet the appetite, rather than suppressing it. “If you look at the literature on imagination and eating, thinking about [a specific food] leads people to desire it more,” says lead author Carey Morewedge, assistant professor of social and decision sciences at Carnegie Mellon University. “But when you eat a lot of a food, you desire it less. What’s the difference between these two experiences?”

The key may lie in the repetition. For the study, Morewedge and colleagues conducted five different experiments with 51 participants in each. In the first experiment, people were divided into three groups and asked to imagine performing 33 consecutive tasks: inserting 30 quarters into a laundry machine, then eating three M&Ms; inserting three quarters into a laundry machine, then eating 30 M&Ms; or inserting 33 quarters into a laundry machine. Then, all groups were given a real bowl of M&Ms from which they were allowed to sample freely.

The researchers found that the people who imagined eating 30 M&Ms ate about half as much candy in real life, compared with the other two groups. There was no difference in actual consumption between those who imagined eating three M&Ms or no M&Ms. (More on Time.com: Mind Over Matter: Can Zen Meditation Help You Forget About Pain?)

It doesn’t take much imagination to conceive that these findings could aid the development of real-world behavioral techniques for dieters — and anyone else dealing with craving — who need help fighting the urge for more. Conversely, the findings could be applied to help people reduce phobic-responses to fear-inducing stimuli like, say, spiders. “I think this is a very nice study, an impressive demonstration that shows the power of imagery, the power of imagination,” says Kent Berridge, professor of psychology and neuroscience at the University of Michigan-Ann Arbor, who was not involved with the research.

Researchers repeated the M&M experiment, this time combining visualizations of eating either M&Ms or cheddar cheese cubes. The goal was to test whether the imaginary eating resulted in habituation to specific foods or to a more general feeling of “fullness” that resulted in less consumption. As expected, people who imagined eating 30 cheese cubes ate less actual cheese than those imagining eating three, when presented with the real food. But people who imagined eating either three or 30 M&Ms showed no difference in later cheddar-cheese consumption.

This might help explain why you can be sure you couldn’t eat another bite of Thanksgiving turkey — but still have plenty of room for pumpkin pie. (More on Time.com: Special Report: Overcoming Obesity)

In yet another iteration of the experiment, people were asked to think about either eating M&Ms or moving an equal amount of the candies one-by-one into a bowl. In this case, researchers found, the more people imagined moving M&Ms (30 times versus three), the more M&Ms they ate in real life. But in the imagined-eating group, the more people visualized consuming the candy, the less they ate later. “You have to be careful not to just think about the taste and smell, and what the food looks like,” says Morewedge, explaining that this kind of “priming” can increase desire for it. “You have to think about actually chewing biting and swallowing food repeatedly for the effect to work.”

Of course, for dieters or others who battle cravings, this presents a dilemma. Once the thought of a food has triggered immediate desire, it can be hard to think your way out of it. “There’s a danger if you just think of the food and the flavor, it will prime you and make you want it more,” Berridge agrees.

In drug recovery programs, this is why addicts are told to avoid “people, places and things” that might remind them of drugs and set off an urge to use. To quash the craving once it’s set in, however, addiction experts advise “thinking it through” — that is, considering the negative consequences, not just the momentary high, associated with drug use. Perhaps, based on the new study, recovery treatment could include asking addicts to think about the details of drug-taking over and over in a repetitive loop; but whether that technique could habituate people to drugs as well as to food remains to be studied. (More on Time.com: Top 10 Most Dangerous Foods)

Morewedge is now seeking funding for a similar study to test the power of imagination over nicotine cravings in smokers. He and his colleagues are also currently running a variation of the original research, comparing participants with various levels of hunger to see how that affects the results.

Morewedge’s research also sheds light on the way desire works and how the brain distinguishes between “liking” and “wanting” a food — or any experience, thing or person. In a final experiment, participants were asked to rate how much they liked cheddar cheese before and after imagining eating three or 33 cheese cubes; they were also asked to play a computer game in which they could click on an image of a cheese cube to earn cheese. Again, people who had imagined eating more cheese clicked less for real cheese, showing that they wanted less of it. However, their ratings of how much they liked cheddar cheese remained the same, before and after.

Berridge notes that in the real world when people eat foods to the point of not wanting it anymore, their liking for the food tends to decline a bit as well. “Where people are loaded with actual food, it suppresses both wanting and liking but wanting goes down further,” he says. “It’s striking in this case that you can lower wanting at all just by imagining food.” (More on Time.com: Overeating: Is It an Addiction?)

In addiction as well, wanting escalates out of proportion to liking: it’s not that the drug or food experience becomes more likeable or feels better and better; instead, desire and craving skyrocket. Ultimately, people find themselves intensely wanting an experience that no longer feels overwhelmingly pleasurable — in fact, it simply feels normal or even sometimes negative. By figuring out exactly how the brain processes these different strands of pleasure and desire, craving may one day be conquered.

Meanwhile, you can try imagining eating Christmas candies and desserts over and over and over, until it feels about as desirable as another rendition of “Feliz Navidad” — and perhaps spare your waistline this holiday season.

More on TIME.com:

How We Get Addicted

Why Parenting is Addictive

Is My Baby Too Fat?