I have to walk how many miles to burn off this soda?
Showing what it takes to burn calories helps teens make healthier choices, Johns Hopkins research shows
Adolescents who saw signs explaining the number of miles they would need to walk to burn off the calories in a sugary drink were more likely to leave the store with a lower calorie, healthier, or smaller size beverage, according to new research from the Johns Hopkins Bloomberg School of Public Health. And those healthier choices persisted weeks after the signs came down.
A report on the findings, published online in the American Journal of Public Health, adds to the growing evidence suggesting that simply showing calorie counts on products and menus isn't enough to break Americans from their bad eating habits. With calorie counts expected on menus in chain restaurants having more than 20 outlets by early next year, as mandated by the Affordable Care Act, the researchers say policymakers may need to rethink how that information is communicated.
"People don't really understand what it means to say a typical soda has 250 calories," says study leader Sara N. Bleich, an associate professor in the Bloomberg School's Department of Health Policy and Management. "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 are needed to burn them off, you can encourage behavior change."
For six-week stretches between August 2012 and June 2013, Bleich and her colleagues installed signs in six corner stores in low-income, predominantly black Baltimore neighborhoods. The signs, four in all, presented a key fact about the number of calories in a 20-ounce bottle of soda, sports drink, or fruit juice: that each bottle contained 250 calories, had 16 teaspoons of sugar, would take 50 minutes of running to work off those calories, or would take 5 miles to walk off the calories. Researchers observed 3,098 drink purchases by black adolescents between the ages of 12 and 18 and interviewed 25 percent of them after leaving the store about whether they had seen and understood the signs. Of the 35 percent who said they had seen the signs, 59 percent said they believed them, and 40 percent said they changed their behavior as a result.
The researchers posted the brightly colored 8.5-by-11-inch signs with the calorie information, displaying one sign at a time, on beverage cases in full view of customers. Before the signs were put up, researchers found that 98 percent of drink purchases in the stores were sugary beverages; after, the number dropped to 89 percent, regardless of the type of sign the adolescent had seen. When compared with purchasing behaviors during times when there was no signage, the most effective sign, Bleich says, was the one telling shoppers they would have to walk 5 miles to burn off the drink calories.
Overall, the number of sugary drink calories purchased went from 203 before the miles-of-walking sign to 179 after. The size of the purchases also fell, from 54 percent buying more than 16 ounces to 37 percent. Regardless of which sign was posted, the percentage of adolescents who chose to buy no beverage at all increased from 27 percent to 33 percent over the study period. Water purchases increased from 1 percent to 4 percent.
"This is a very low-cost way to get children old enough to make their own purchases to drink fewer sugar-sweetened beverages, and [the signs] appear to be effective even after they are removed," Bleich says. "Black adolescents are one of the groups at highest risk for obesity and one of the largest consumers of sugary beverages. And there is a strong scientific link between consumption of sugary beverages and obesity. Using these easy-to-understand and easy-to-install signs may help promote obesity prevention or weight loss."