Elizabeth Gross Cohn, an assistant professor at the Columbia University School of Nursing, and colleagues studied the calorie counts for 200 food items on menu boards in fast-food chain restaurants in the New York inner-city neighborhood of Harlem.
New York City had a standard menu labeling law since 2006 that includes some, though not all, of the new federal requirements.
"Although most postings were legally compliant, they did not demonstrate utility," Cohn said in a statement. "Menu postings for individual servings are easily understood, but complex math skills are needed to interpret meals designed to serve more than one person. In some items, calories doubled depending on flavor, and the calorie posting did not give enough information to make healthier selections."
For example, a bucket of chicken was listed as 3,240 to 12,360 calories, but the menu board did not contain enough information to determine the number of pieces of chicken in a serving size, Cohn said.
The federal law passed in March 2010 requires restaurants with 20 or more locations to provide calorie data and additional nutritional information for menu items. The U.S. Food and Drug Administration is currently considering how best to guide chain restaurants in posting calorie counts on menu boards.
The study published in the Journal of Urban Health suggested federal rules require the labeling be understandable and provide useful calorie information for posted menus.