If your breakfast sandwich has 450 calories without meat, but 600 calories with meat added, would you go for the one with fewer calories? Chances are, you wouldn't.

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That's according to a new study recently published in the American Journal of Public Health.

"I think a lot of people do use the information. Usually people who already are trying to watch what they eat really like having that information available," said Julie Downs, Associate Research Professor of Decision Science at Carnegie Mellon and lead author of the study.

"What it doesn't seem to be achieving is leading to some great reduction in calories that people are eating across the population. We still have large populations who are eating far more calories than they should and the labels don't seem to be bringing that down. Even adding recommendations didn't help."

"It's a nice thought that people are eating too much only because they don't know how many calories are in their food, but eating decisions are really complicated and there are a lot of reasons people eat what they do even if they do know what's in it. Maybe they don't care how many calories are in their food," said Downs. "Sometimes, if people are running out to lunch during work, they only have a certain amount of time and run to get the closest thing and that may not necessarily be the healthiest."

Several states and municipalities across the country have already introduced mandatory menu labeling. Soon, nationwide regulations will go into effect as the result of a new health care law. While well intentioned, the new data show that providing the calorie count does not help people make healthier choices.

So, what can restaurants do to encourage the healthier options?

"It's really difficult. There are some things that are being tried. Some places are providing information like how many minutes you have to exercise to work off this particular menu item, or traffic lights. A green light is for something that's healthier. A red light is for something that's a little unhealthier. It may be more beneficial for restaurants to introduce monetary incentives to nudge people toward the healthier options."