The newest diet tool is a mirror. No, not to scowl into as you critique the tummy bulges that appeared over the holidays. This mirror is for watching yourself eat.

The principle at work here is that if we sit in front of a mirror watching ourselves stuff food into our mouths, we will eat less junk food and more fruits and vegetables.

The diet was cooked up by a marketing researcher at the University of Central Florida who studies consumer decisionmaking. In a report published in the January issue of the Journal of the Association for Consumer Research, professor Ata Jami concluded that when people watch themselves in a mirror, they “judge themselves and their behaviors in a same way that they judge others.”

The criticism influences the way the food tastes, he said. If we feel bad about what we’re eating, it doesn’t taste as good. Likewise, if we feel good about our choice of food, it will tend to taste better.

Jami conducted an experiment in which he told graduate students that they were part of a taste-testing. Half the subjects were served a slice of chocolate cake on a table in front of a mirror; the other half got cake in a room with no mirror. The first group didn’t rate the taste of the cake nearly as high as the second group did.

Jami tried the experiment again with fruit. This time there was no difference reported in the tastes.

“The presence of a mirror induces a discomfort and lowers the perceived taste of the unhealthy food,” he wrote. “Eating healthy does not induce any discomfort and, as a result, [the] mirror does not change the taste of healthy food.” □