Want to eat healthier? Use color coding.

In an effort to get staff to eat better, a team of Massachusetts General Hospital (MGH) researchers restructured the main hospital cafeteria. They made two small changes, and those made a world of difference.

Since 2010, MGH has attached color coded labels to all items: green for the healthiest, yellow for less so, and red for the least healthy. The second move came a few months later, and involved rearranging the fridges and food racks. Healthier food was placed at eye level, and the less healthful was knocked down a level.

Want to eat healthier? Use color coding.

The first change led to a reduction in the sale of the red items by 23.8%, and the second lowered sales by another 14.2%. Green purchases, on the other hand, slightly improved, by 5.6% then 2.3%.

What the paper also notes is that these changes occurred for workers of all ethnic and educational backgrounds. While some other attempts at labeling had been less effective among certain groups, these two methods seem to have worked across the board.

If you're curious how the researchers decided on how to color code items, here's the official methodology:

Every item was labeled green, yellow, or red, and was rated on three positive (fruit/vegetable, whole grain, or lean protein/low-fat dairy as the main ingredient) and two negative criteria (saturated fat content and caloric content). Items with more positive than negative criteria were green ("consume often"). Items with equal numbers of positive and negative criteria or only one negative were yellow ("consume less often"). Items with two negative and no positive criteria were red ("there is a better choice in green or yellow"). Water and diet beverages with 0 kcal were green, despite having no positive criteria.