That our national food consumption patterns are in need of a dramatic overhaul is indisputable – almost 17 percent of children and 35 percent of U.S. adults are obese, percentages that are only rising. How to go about enacting this much-needed change, however? That's where the uncertainty comes in.

To date, few public policies have been enacted in an effort to change our national eating habits. One notable exception is the U.S. Food and Drug Administration's announcement that food outlets with more than 20 locations must list calorie counts on their menus by December 2016.

But does this approach actually lead consumers to make healthier choices? A new study, conducted by researchers at NYU Langone Medical Center, serves up the grim conclusion that calorie labels, on their own, do not reduce the overall number of calories ordered.

Related: FDA Extends Deadlines for Chain Restaurant to Add Calorie Counts to Menus

The study, published today, compared itemized orders from fast-food chains in New York City -- which, in 2008, became the first jurisdiction that required chains with more than 15 locations to post calorie labels on menus – with orders at fast-food chains in New Jersey (where there are no calorie labels on menus) in 2008 and then again in 2013-2014. As such, it's the first long-term analysis of the effects of menu labeling in the United States.

In 2008, directly after calorie information appeared on menu, 51 percent of polled fast-food diners in New York City said they noticed calorie information and 12 percent said they used it to order fewer calories, versus 14 percent and 2 percent of New Jersey fast-food diners – percentages that remained fairly consistent in 2013-2014.

Despite this, the average number of calories per order remained the same. According to the study, there was "no consistent change in the nutritional content of foods and beverages purchased or in how often respondents purchased fast food." What's more, between 2008 and 2013-2014 the average number of calories purchased increased for diners in both New York City and New Jersey.

Earlier studies have suggested the effects of calorie-labeling at fast-food restaurants are minor at best, but there was a hope that the long-term impact would be more substantial. "We did not find that to be the case," the authors wrote.

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While this is certainly a blow to the idea that nationwide calorie menu requirements will dramatically alter the way America eats, it doesn't necessarily mean the policy is useless: perhaps, as the authors speculate, it may be more effective in sit-down restaurants where dining expectations are different, or for specific groups of particularly health-concious diners. "We will have to wait and see, while continuing to monitor and analyze the policy’s impact," Brian Elbel, the study's senior investigator, said in a statement.

Still it’s disheartening news, one that demands the consideration and implementation of additional strategies if obesity rates are ever to significantly fall. Previous research suggests more dramatic label modifications – such as using a stop sign for very unhealthy foods, listing the amount of exercise required to burn off each menu item or adding context by placing calorie counts next to the recommended number of calories in one meal – could be effective at changing consumer behavior.

Sadly, as the authors rightly note, "the likelihood of their being adopted at a policy level is limited."

Related: U.S. Nutrition Labels Get a Makeover, But New Version Won't Be Seen for Years