There’s a reason why stop signs are red. Not only is it the most noticeable color, but study after study has found that, because stop signs have been red for such a long time, the color itself has come to automatically signal “danger”…“don’t go here”… and, yes, “stop.” And now new research shows that this color even might help us stop drinking fattening beverages and eating too much food.

We have known for a long time that colors can influence our moods and even our behaviors, but it was Leonie Reutner, MSc, a doctoral student and lecturer at the University of Basel in Switzerland, who coauthored a study published online inAppetite this past January to see if color could actually be used as a tool for weight loss. The answer? Yes. But how?

SEEING RED

Knowing how the color red signals “danger” in most people’s minds, Reutner and her colleagues wanted to see whether using red-colored plates and red-labeled glasses would make people eat less of a salty snack and drink less of a sugar-sweetened beverage. So they set up two experiments to find out…

The beverage study: Researchers approached 41 college students and invited them to take part in an “evaluation of three sweet drinks.” Since their pretest had found that female students took only tiny sips of the drinks, the researchers invited only male students to participate. Each participant was asked to rate three drinks matched for color (slightly yellowish) in clear plastic cups. An adhesive label with a large A, B or C printed in white on it was attached to each cup. The backgrounds behind the letters on each label were, randomly, blue or red. The drinks were not identified to the study participants, but they were lemon-flavored, white tea-flavored and green tea-flavored. Researchers weighed each cup before and after the drink test and found that—you guessed it—regardless of which drink was being tasted, participants drank significantly less (about 41% less, on average) from the red-labeled cups than from the blue-labeled cups.

The red-plate study: This time, 109 males and females, ranging in age from 13 to 75, were asked to assist in a study related to “various areas of psychology.” Each was given a questionnaire to complete, was seated at a table in front of either a white, red or blue paper plate containing exactly 10 pretzels, and was told, “Feel free to snack on the pretzels while completing the questionnaire.” After the participants left, researchers counted the pretzels that were left on each plate. And, sure enough, participants ate 48% fewer pretzels from red plates than from the blue and white plates.

WHAT CAN WE READ INTO RED?

Before anyone goes out and buys red plates and cups, Reutner said, it’s important to consider two points. The first is that the participants in the experiments didn’t know ahead of time that red might help them eat or drink less, but now that you know it, the red might not have the same effect on you. The second is that the participants were distracted during the experiment. They were focused on either rating a beverage or filling out a questionnaire as opposed to being focused on what they were eating…so again, your results might vary.

I applaud Reutner for being academically rigorous in pointing out these differences between her study and real life—but on the other hand, the red had such a huge effect in the study that it’s hard to imagine that it wouldn’t have some effect on our dinner tables.

So if you want to lose weight or if you want to help a loved one lose weight, why not try it? Get some red plates and give it some time—maybe a month—for the novelty to wear off, and then judge whether they are helping you. And while you’re at it, get smaller plates—size has also been shown to matter when it comes to quantity of food eaten.

Source: Leonie Reutner, MSc, researcher and lecturer, department of social and economic psychology, University of Basel, Basel, Switzerland.