Who could have known traffic lights could potentially guide not only people driving through traffic, but also people making choices on healthy food as well?

Apparently the Sound Bites Café of National Public Radio in Washington, D.C. had an idea that this was so. When it moved to its new headquarters, it also got a new cafeteria, and color-coded labels for the food offerings started popping up. Green labels meant, "Choose Often," and were placed on food that were proven to be low-fat and healthful. Yellow meant, "Good Choice," for acceptable entrees like rice. Read meant, "On Occasion," and were placed on high-carb choices and those that were packed with salt, fat, and calories.

The idea was eventually adopted by the administrators of Massachusetts General Hospital in Boston, in its own cafeteria. The cafeteria was redesigned with this traffic-light color-coding system in mind, and the food arrangements and displays were redone so that the ones labeled green are most visible in the front, and at eye level. The cafeteria handles very high traffic, averaging 6,511 transactions a day.

Anne Thorndike, the hospital's primary care physician and also an assistant professor of medicine at Harvard Medical School, tracked the effects of such a system on everyone who dined and purchased from the cafeteria for two years. She found that the cues made patrons more aware of which food was good and bad for them, and after about six months, people started changing their eating habits. There was a 20 percent decrease in the purchase of red-labeled items, and purchase of green-labeled items rose by 12 percent. Also, sale of sugary sodas dropped by 40 percent, and these much healthier eating choices lasted for the entire duration of the study. These findings were published in the American Journal of Preventive Medicine.

"I don't want to over-claim that this is a weight-loss program," Thorndike says. "But if there is an employee that was buying a 20-ounce Coke, three times a week and/or every day, and they reduce their calories by 200 a day because of the traffic-light labels, then you could argue that it's helping that person lose weight. It has the potential."

The traffic lights and shelf changes in the hospital cafeteria did not harm total sales, and only affected food choices. The study states that this system can be one more way in which the food industry can take part in the fight against obesity without compromising profits. This system is also simple enough and easy enough to implement in the home, since the red-yellow-green color code has become instinctive in people and applies to so many other things.