SUNDAY, March 29, 2015 (HealthDay News) -- Highly processed foods account for more than 60 percent of the calories in products Americans routinely buy in grocery stores, a new study finds.
These foods tend to have more fat, sugar and salt than less-processed foods, the researchers said.
"Overall, we found that not only are highly processed foods a dominant, stable part of U.S. purchasing patterns, but also that the highly processed foods that households are purchasing are higher in fat, sugar and salt, on average, compared to the less-processed foods that they buy," study author Jennifer Poti, a research assistant professor at the University of North Carolina at Chapel Hill, said in a news release from the American Society for Nutrition.
Poti's team analyzed at least one year of grocery store purchases by more than 157,000 households between 2000 and 2012. The participants took part in the study for an average of four years and collectively bought 1.2 million items.
Highly processed foods include items such as prepared meals, white bread, cookies, chips, soda and candy. Unprocessed or minimally processed foods include fresh or frozen vegetables, fresh meat, milk, eggs and dried beans.
From 2000 to 2012, the proportion of calories bought in highly processed foods remained stable at 61 percent to 62.5 percent. There was a significant increase in the proportion of calories bought in ready-to-heat foods (such as frozen meals), reaching more than 15 percent in 2012, the investigators found.
The findings were scheduled for presentation Saturday at the Federation of American Societies for Experimental Biology annual meeting, in Boston. Research presented at meetings should be viewed as preliminary until published in a peer-reviewed journal.
"Many Americans have strongly held opinions and beliefs about processed foods," Poti said in the news release.
"Some consider processed foods to be tasty, convenient and affordable choices while others contend that the combination of sugar, fat, salt and flavoring in these foods promotes overeating and contributes to obesity. But until now, we didn't really have the evidence needed to settle this debate," she explained.
Poti said there is a need to distinguish between processed and highly processed foods.
"It is important that when we discuss processed foods, we acknowledge that many processed foods, such as canned vegetables or whole-grain breakfast cereals, are important contributors to nutrition and food security. However, it is the highly processed foods . . . that might potentially be related to obesity," Poti said.
The U.S. Centers for Disease Control and Prevention has more about nutrition.