Red light, green light — we all know what those mean. And when Harvard researchers added traffic-light symbols to packages and menus in a hospital cafeteria, they found that diners bought healthier foods with fewer calories. The findings were published online July 10, 2019, by JAMA Network Open. Scientists first tracked the cafeteria purchases of hospital employees for a few months. Then they labeled foods with symbols indicating if a food was healthy (green), less healthy (yellow), or unhealthy (red); moved unhealthy foods to less accessible locations in the cafeteria; and tracked purchases for another two years. About 5,700 people bought food during that time. When researchers linked calorie information to purchases, they found a 6% decrease in calories per purchase over two years, including a 23% decrease in calories from the least healthy foods. This builds on previous research that found sales of red-stickered items dropped by 4% and sales of green-stickered items grew by 5% during the study. Can you try this at home? Maybe not the traffic-light stickers. "But making it harder to access unhealthy foods gives you enough time to think about your choice before eating something that is not consistent with your goals," says lead author Dr. Anne Thorndike, who specializes in obesity treatment and prevention at Harvard-affiliated Massachusetts General Hospital. "Strategies include having a drawer for the unhealthy foods, placing unhealthy snacks high on a shelf, and having a goto' shelf for healthy snacks."
Image: lcs813/Getty Images
As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review or update on all articles. No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.