A Disappointing Meal Can Change Your Whole Mood

We all know this, but now scientists have proven it. Food that pleasantly surprises you—or really disappoints you—can entirely change your mood.

It's all about expectation. New research published in Food Research International shows that when you take a bite out of something expecting it to be great but it's not, your mood can entirely shift. And vice versa.

A team of researchers from the Netherlands, Finland, and Austria got together and fed people yogurt. They looked at the emotional effects it had on the eaters. Here's how the study worked: Three groups of participants were each given a pair of yogurts to taste. The yogurts were the same brand but had different flavors or fat content. The team then tested the subjects' emotions using a new emotive projection test.

And this is what the study found: liking or being familiar with a product had no effect on a person's emotion. Instead, what did affect mood was a change in whether the participant liked the yogurt after tasting it, as compared to what they expected. Being pleasantly surprised or harshly disappointed about food was found to influence people's moods.

The emotive projection test used in this study examines mood in an unusual way. The researchers showed study participants photographs of people and asked them to rate the photographed people on six positive and six negative traits.

Scientific evidence shows that people will project their emotions onto others. So if they rate the people in the photographs as having a lot of negative traits, it says something about the participants' mood. In other words, their judgment of others will indicate their own mood.

The researchers were particularly pleased to find a methodology for examining the emotional effect of food on people without merely asking them whether they enjoyed the food or not. "We were surprised to find that by measuring emotions, we could get information about products independent from whether people like them," said lead author of the study Dr. Jozina Mojet, from Food & Biobased Research in the Netherlands. "This kind of information could be very valuable to product manufacturers, giving them a glimpse into how we subconsciously respond to a product."

The researchers also examined the sensory effect of the yogurt. They found that low-fat versions led to more positive emotional responses—something no one would have guessed. Also, they were quite struck by the strong positive emotional response elicited by vanilla yogurt.

They probably shouldn't have been surprised. Earlier studies have shown that a subtle vanilla scent in places like hospital waiting rooms can reduce aggression. It can also positively affect relationships among patients and between patients and staff.

So what will become of these new findings?

"We were looking for a valid, quick and not too expensive and time-consuming method to measure the emotions or mood changes evoked by food," said Dr. Mojet. "This sort of implicit method can reveal the complex interactions between the different factors involved in a situation, which, based on his or her memory and expectations, is given meaning by the person under investigation."

So soft-serve freaks of America, rejoice. Put the Cymbalta, Zoloft and Prozac aside, and instead, pick up some low-fat, vanilla fro-yo. Don't have particularly high expectations? Perfect. Get ready to watch your mood rise.