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BALTIMORE — Americans love convenience. From drive-thru restaurants to ready-to-heat meals, our food system has evolved to prioritize speed and simplicity. But a concerning trend has emerged in recent years: ultra-processed foods now dominate American diets, and not just when dining out.

A study published in the Journal of Nutrition reveals that ultra-processed foods (UPFs) make up more than half of Americans’ energy intake regardless of whether they’re eating at home or away from home. Even more alarming, the research shows that while the proportion of calories from UPFs is increasing over time, consumption of minimally processed foods is steadily declining.

The study, conducted by researchers from Johns Hopkins Bloomberg School of Public Health and other institutions, tracked the eating patterns of over 34,000 American adults between 2003 and 2018, providing one of the most extensive analyses of how food processing levels have changed in American diets.

‘More than just junk food’

“The perception can be that ‘junk food’ and ultra-processed foods are equivalent,” says lead study author Julia Wolfson, Ph.D., associate professor in the Bloomberg School’s Department of International Health, in a statement. “Yet ultra-processed foods encompass many more products than just junk food or fast food, including most of the foods in the grocery store. The proliferation and ubiquity of ultra-processed foods on grocery store shelves is changing what we are eating when we make meals at home.”

Ultra-processed foods are industrial formulations that contain substances with little or no nutritional value, such as colorings, emulsifiers, artificial flavors, and sweeteners. Examples include packaged snacks, sugary cereals, chips, hot dogs, prepackaged meals, and many types of bread. By contrast, minimally processed foods include fruits, vegetables, whole grains, eggs, milk, and other foods that undergo minimal processing, like freezing or simple packaging, without adding substantial ingredients.

The researchers discovered that throughout the study period, UPFs consistently made up more than 50% of energy intake for Americans both at home (increasing from 51.4% to 54.1%) and away from home (rising from 58.9% to 60.6%). Meanwhile, minimally processed foods declined from 34.8% to 29.8% of at-home calories and from 28.1% to 24.0% of away-from-home calories.

Many might assume that fast food and restaurant meals drive America’s ultra-processed diet, but this research highlights that our grocery carts and home kitchens are equally problematic. In fact, the proportion of total energy intake from UPFs consumed at home increased significantly (from 33.6% to 37.1%) over the study period, while UPF intake from away-from-home sources remained relatively steady.

Ultra-processed food consumption similar among demographics

The researchers found only minor differences in trends of ultra-processed food intake at home by sex, age, race/ethnicity, income, and education over the study period. UPF intake was slightly lower than 50% in some years for Hispanics and higher-income households. However, even in these groups, the proportion of at-home calories from ultra-processed foods never fell below 49% for the high-income group or 47% among Hispanics.

For those with less than a high school degree, away-from-home consumption of ultra-processed foods rose nearly eight percentage points, from 59.2% in 2003 to 67.1% in 2018. That proportion hovered around 60% for individuals with a high school degree or more. This widespread reliance on ultra-processed foods across all groups suggests that broader societal factors like food marketing, availability, and pricing are driving these dietary patterns, rather than simply being a matter of personal choice.

Consuming high amounts of ultra-processed food has been linked to chronic health conditions such as cardiovascular disease, obesity, and colorectal cancer, among others. The nutritional profile of UPFs often includes high levels of added sugars, unhealthy fats, and sodium, while lacking fiber, vitamins, minerals, and other beneficial compounds found in less processed foods.

Home-cooked meals don’t always mean healthier

The study’s findings challenge the notion that simply encouraging more home cooking will automatically lead to healthier eating. Even households that report cooking dinner frequently still derive most of their calories from ultra-processed foods. This suggests that modern “cooking” often involves combining and heating ultra-processed components rather than preparing meals from minimally processed ingredients.

Several factors explain the declining consumption of minimally processed foods. Overall, the proportion of total calories from minimally processed foods fell nearly five percentage points from 33.2% in 2003 to 28.5% in 2018. Minimally processed foods tend to be more expensive, more perishable, less available in some communities, and require more cooking skills or pre-planning. By contrast, ultra-processed foods are easier and faster to prepare, often less expensive, and more shelf stable.

“We need strategies to help people choose less processed foods and avoid unhealthy ultra-processed foods for foods purchased for both at-home and away-from-home consumption,” adds Wolfson. “Additionally, strong nutrition labels warning of high ultra-processed food content may be warranted.”

‘Backbone of American diet’

Rather than focusing solely on restaurant meals or fast food, interventions must address the entire food environment. This might include improving food literacy and cooking skills, implementing front-of-package warning labels for UPFs, making minimally processed foods more affordable through subsidies or incentive programs, and encouraging food manufacturers to improve the nutritional quality of processed products.

For individuals concerned about their diet, the study serves as a reminder to examine not just where they eat but what they eat. Whether dining out or preparing meals at home, choosing less processed options could contribute to better long-term health outcomes.

When looking at your own eating habits, consider not just how often you cook at home versus eating out, but what ingredients you’re actually using when you prepare meals. A home-cooked dinner assembled from packaged, ready-to-heat components may not offer much nutritional advantage over its restaurant counterpart.

The study’s bottom line is sobering but important: ultra-processed foods have become the backbone of American diets, regardless of where meals are consumed. Reversing this trend will require attention to both at-home and away-from-home eating environments, with coordinated efforts from individuals, industries, and policymakers. In a food industry where processing has become the norm rather than the exception, finding a path back to more minimally processed options presents a significant but essential challenge for public health.