University of North Carolina scientists are mapping the United States to determine what items consumers are buying and eating and how many overall calories they're consuming, based on different regions of the country.

They hope the information they gather can be used by consumers, food companies, researchers and government help address dietary issues.

Until now, the only information about consumers' caloric intake and food choices has been from government data, which frequently lags months or years behind the rapidly changing landscape, according to a news release.

One of the unique features of the UNC database is its ability to sort one product into thousands of brands and variations.

The project, started in 2010, stems from first lady Michelle Obama's campaign to combat obesity and the accompanying pledges of 16 major food companies.

Those companies vowed to reduce the calories they sell to the public by 1.5 trillion.

The Robert Wood Johnson Foundation agreed to fund the study with $6.7 million to hold the companies accountable, according to the release.

Barry Popkin, a professor at the UNC School of Public Health, Chapel Hill, is leading the team that has taken existing commercial databases of food items in stores. The information also includes purchase scanner data on 600,000 different foods.

The team then matched that information to nutritional facts on the back of packages and government data on individuals' dietary intake.

But it doesn't include restaurant means, which represents about one-third of American diets, or some prepared foods.

The enormous database has taken nearly three years to construct.

"The country needs something like this, given all of the questions about our food supply," Popkin said in the release. "We're interested in improving the public's health, and it really takes this kind of knowledge."

The project already has shown light on the evolving food market, which tends to change about 20 percent annually.

One trend, for example, is companies are increasingly substituting fruit juice concentrate for sugar.

Although the fruit-based sweetener may cater to consumers seeking more natural foods, it isn't necessarily healthier than other sugars, according to the release.

The Healthy Weight Commitment Foundation, which represents the 16 food companies, says it will report this summer on how successful it's been in reducing consumption by 1.5 trillion calories.

The first results from Popkin's study aren't expected until later this year.