If you want to lose weight, eat that cake in front of a mirror

A new study has found that watching yourself eat something unhealthy, like a slice of chocolate cake, can make that food seem less tasty. And that, in turn, might make you eat less.

Ata Jami, a marketing professor at the University of Central Florida who studies consumer behavior and decision-making, looked at whether mirrors affected how two groups of undergraduate students ate.

Under the guise of a taste test, all were asked to choose between a piece of chocolate cake (a common supermarket brand) and a container of fruit salad (from a can). Half of the 185 students were randomly chosen to sit in a room facing a mirror. 

The other half were put in a space where they couldn't see themselves. After sampling their selection, participants were asked questions about the food and if they'd want to have it again.

Those in the room with the mirror were told it was part of a different experiment about fashion and couldn't be moved. "We didn't want them to be suspicious of the mirror," Jami said.

The students eating cake in front of the mirror, it turned out, liked the dessert less than those who couldn't see their reflection. There was no such difference for the fruit-salad students.

Something happens when people view themselves in a mirror, Jami explained. On appearance, for example, they compare how their hair looks to how they think it should look. Same with behavior.

"You don't want to see yourself eating unhealthy products because that does not match with standards of healthy eating," he said. The disconnect makes people feel uncomfortable -- even if they don't realize why.

Here is what's going on in their heads: "They are looking for a reason for why they're not feeling so good, so they think, 'maybe there is something wrong with the food,'" Jami said. They look for an external factor to blame, which makes it easier to "tolerate that negative feeling."

So would putting up mirrors in your own home really help you cut out those unhealthy snacks?

Jami thinks so. People can add them in places like the kitchen, where a glance in the mirror might push them to reach for an apple instead of a bag of potato chips.

Restaurants might want to consider more mirror decorations, too, to encourage a shift in diners' menu selections. And if the profit margin is higher on healthier salads than decadent desserts, even better for them.

There is a silver lining for those of us who really like chocolate cake. Jami conducted a related experiment with the students and found that if someone else picked a less healthy item (brownies instead of fruit salad), the others didn't feel any discomfort about eating the brownies.

"If friends give it to you, it's guilt-free," he said.

The research is to be published in the January issue of the Journal of the Association for Consumer Research.