Imagine yourself standing at the counter in a fast food restaurant reading a menu board that not only tells you how many calories are in each item, but also tells you how many miles you would have to walk to burn off those calories. Would it make a difference in what you ordered?

Researchers from the University of North Carolina at Chapel Hill set up a study to answer that question, and it appears that understanding just how much exercise we have to do to burn off calories may be one of the best diet strategies yet.

On the menu: a burger that contained 250 calories and required 78 minutes of walking or 2.6 miles to burn off those calories.

Over 800 mostly female, middle-aged volunteers completed a survey that had them select a meal based on the online menus of common fast food restaurants. The participants were randomly assigned to one of four groups. Each group was given a different menu format: a menu with no nutritional information; a menu with calorie information; a menu with calorie information plus the minutes of walking needed to burn off the calories; and a menu with calorie information plus the miles of walking needed to burn off the calories. For example, one of the items was a burger that contained 250 calories taking 78 minutes of walking or 2.6 miles to burn off those calories.

People who chose from the menu with no nutrition information ended up with a meal that contained around 1,020 calories, approximately half of a woman’s daily calorie needs and 40 percent of a man’s. Those who were given only the calorie content chose foods averaging 927 calories. When the participants saw how many minutes they would have to walk to burn off the calories, their intake dropped to an average of 916. But when they had to face how many miles they would need to walk to burn off their food choices, they chose a meal with about 826 calories.

The label that was the most effective at encouraging lower calorie intake was the one displaying the miles needed to walk off the calories. But when asked which menu format they preferred, 47 percent of the participants chose the menu with calories and minutes of walking, while 37 percent said they liked the menu that showed calories with miles of walking. Clearly, menus that showed the amount of physical activity required to burn calories were preferred over menus that showed only calories or no nutrition information whatsoever.

Most of the participants did not seem to understand what calories mean, or how the caloric content of food fits into their overall daily caloric intake; and they may not even know how many calories they should consume, according to the researchers. Only 8 percent correctly answered the three calorie literacy questions that were included in the survey, suggesting that there is a need for public health education on calorie literacy.

The study was published in the journal, Appetite.