Easy-to-understand signs that explain how many miles would need to be covered in order to burn off calories from soda prompted adolescents to choose lower-calorie beverages. These healthier choices continued even after weeks of the signs being taken down.

Sara N. Bleich, PhD, associate professor in the Department of Health Policy and Management at Johns Hopkins University Bloomberg School of Public Health, led a study which involved installing signs in six corner stores in low-income, mainly black neighborhoods in Baltimore.

The signs listed details about a 20 oz. bottle of soda, sports drink or fruit juice: that each bottle contained 250 calories and 16 teaspoons of sugar. The signs also stated that it would take 50 minutes of running to burn off those calories, or five miles of walking to work them off.

Among the 35 percent of adolescents between the ages of 12 and 18 who said they saw the signs, 59 percent said they believed them, and 40 percent reported a change of behavior as a result.

The size of the purchases was also reduced from 54 percent buying over 16 oz. down to 37 percent. The percentage of adolescents who decided not to buy any beverage at all increased from 27 percent to 33 percent over the study’s six-week time period. Water purchases increased from one to four percent.

“People don’t really understand what it means to say a typical soda has 250 calories. If you’re going to give people calorie information, there’s probably a better way to do it. What our research found is that when you explain calories in an easily understandable way such as how many miles of walking needed to burn them off, you can encourage behavior change,” said Bleich in a statement.

The findings of the study are published online in the American Journal of Public Health.