Calorie counts on restaurant menus, especially when it comes to fast food, was expected to help consumers make healthier choices, but a study by researchers at New York University said such labeling has had an effect on only 8 percent of diners.

The study published Thursday in the Journal of Public Policy & Marketing comes six months before federal regulations requiring calorie labeling goes into effect nationwide.

"Health policies would benefit from greater attention to what is known about effective messaging and behavior change. The success of fast-food menu labeling depends on multiple conditions being met, not just the availability of calorie information," study author Andrew Breck, a doctoral candidate at the NYU Wagner Graduate School of Public Service, said in a press release.

New York City has required calorie labeling since 2006 for fast-food chains, joined by Philadelphia and Seattle shortly thereafter. Nationwide requirements take effect May 5 and will apply to all chain restaurants with at least 20 locations.

So far though, there’s little evidence such labeling has changed consumption habits.

"We know that few regular fast-food eaters chose fast food because it is nutritious; they instead are motivated by cost and convenience," said study author Beth Weitzman, professor of public health and policy at NYU Steinhardt School of Culture, Education and Human Development. "However, requiring restaurants to make the calorie content of their menu items highly visible could cause restaurants to add new, healthy options to their menus."

Part of the problem may be that consumers are oblivious to the labeling or may not know the number of calories they’re supposed to consume in a day. For the information to change consumer behavior, consumers must also be motivated to eat healthy and learn the calorie content is different than expected, and the information must reach consumers. These criteria were developed by researchers at the University of Arkansas and Villanova University.

The researchers used data collected in Philadelphia in 2008 from 699 consumers at 15 fast-food restaurants as well as 702 people surveyed by phone who ate fast food at least once a week. Few of those queried met all five conditions, the researchers found.

A third of those surveyed by phone said they did not see calorie labels and two-thirds of those queried at the eateries said they didn’t notice the calorie information. The researchers suggested making the information more prominent and noticeable.