Dieters take note: thinking in detail about eating can reduce actual food consumption, according to a study in the December 10, 2010, issue of Science. Imagining an experience is known to evoke the same physiological responses as the real experience, so researchers at Carnegie Mellon University tested whether imagining chowing down could simulate the experience enough to satisfy people’s cravings. Study participants thought about eating a food—M&M’s or cubes of cheese—one morsel at a time and then afterward were offered the same food to eat. Those who imagined eating 30 M&M’s ate half as many candies as those who pictured putting 30 quarters into a laundry machine. The effect was specific to the type of food imagined, with those thinking about eating cheese consuming about half the amount of cheese eaten by those who had thought about eating M&M’s.

Although these findings seem counterintuitive given that the sight of a candy machine can set off an intense craving for chocolate, the key difference is in how people think about food, says Carey Morewedge, the psychologist who led the study. “When people are normally thinking about eating food, they’re not imagining the actual consumption,” he says. Indeed, when subjects thought about placing 30 M&M’s into a bowl, they ate 1.6 times more than those who only thought about eating them. But when people engaged in the mental imagery that would accompany actual eating, it wore down their desire to eat. Morewedge plans next to explore whether this kind of mental simulation can help smokers reduce their craving for cigarettes.