The study, published in Nutrition Journal, was conducted by researchers at the University of Gothenburg in collaboration with the Swedish Food Agency (Livsmedelsverket in Swedish). It analyzed data from three Swedish national dietary surveys, comprising 1,797 adults (2010–2011), 3,099 adolescents (2016–2017), and 1,820 young children (2021–2024).

The researchers applied the NOVA system, which categorizes foods according to the nature, extent, and purpose of industrial processing, to determine the proportion of dietary energy derived from UPFs and examine associations with nutritional quality and body weight.

UPF Consumption Estimates Varied Widely Depending on Classification

Because national dietary surveys do not always capture the ingredients, manufacturing processes, or preparation methods needed to classify foods under NOVA, the researchers developed three classification scenarios to account for uncertainty.

Under the primary classification scenario, UPFs accounted for an average of 45 percent of energy intake among adults, 52 percent among adolescents, and 46 percent among young children. However, when a stricter classification was applied, these estimates fell to 23 percent, 26 percent, and 29 percent, respectively. Under the broadest classification, the corresponding estimates increased to 52 percent, 63 percent, and 53 percent.

The differences largely reflected assumptions about foods with ambiguous processing characteristics, such as bread and composite dishes, for which detailed ingredient or preparation information was unavailable.

Bread was the largest contributor to UPF-derived energy among adults and young children, while sandwiches, pizzas, and similar foods contributed the most among adolescents. The researchers noted that some breads were classified as UPFs because they contained ingredients such as isolated gluten or syrup, despite having otherwise favorable nutritional profiles.

The findings highlighted the difficulty of comparing UPF consumption estimates across studies that use different classification assumptions, even when analyzing similar dietary data.

Higher UPF Consumption’s Relation to Diet Quality Depended on Nutritional Indicator

Across age groups, higher UPF consumption was generally associated with greater dietary energy density, higher added sugar intake, and lower consumption of dietary fiber and whole grains. The nutrient density of most vitamins and minerals also decreased as UPF intake increased.

However, the associations were not consistent across all nutritional indicators. Higher UPF consumption was associated with lower dietary salt density across all age groups, while saturated fat intake was not significantly associated with UPF consumption among adults or adolescents.

Among young children, higher UPF consumption was associated with greater iron and vitamin E intake, potentially reflecting consumption of fortified children's cereals, porridge, and similar products classified as UPFs.

Using criteria adapted from Sweden's Keyhole nutrition labeling system, the researchers also found that 8.5 percent of foods classified entirely as UPFs met criteria for “generally encouraged food” choices, demonstrating that processing-based classifications do not always align with dietary recommendations.

No Robust Relationship Between UPF Consumption, BMI

Regarding body weight, each 10-percentage-point increase in dietary energy from UPFs was associated with a 0.61 percent higher body mass index (BMI) among adults in the primary analysis. However, this association was not statistically significant under alternative UPF classification scenarios.

No consistent associations with BMI or overweight and obesity were identified among adolescents or young children. Overall, the researchers concluded that the study did not identify robust relationships between UPF consumption and weight status.

Because the research was cross-sectional, it could not establish whether food processing itself contributed to differences in body weight or whether the observed associations reflected other dietary characteristics.

Findings Add to International Debate Over UPF Definitions and Policy

The findings contribute to an ongoing debate about whether processing-based food classifications provide sufficient information to inform nutrition policy, particularly when foods with substantially different nutritional profiles are grouped together.

For example, a previous report examining the nutritional implications of UPF classification raised concerns that processing categories do not reliably indicate nutritional value. Conversely, research comparing different processed food classification systems found consistent associations between processing categories and nutritional and health outcomes despite differences in how foods were categorized.

The issue has also gained attention among international food policy authorities. The EU has initiated work to develop scientific and ethical opinions relevant to UPF policymaking, with opinions expected by early 2027. Additionally, the Codex Alimentarius Commission has received a proposal to establish a risk analysis framework for diet-related diseases, although the Codex Committee on Food Labeling declined a proposal to initiate work related to UPFs at its 49^th Meeting in May.

The Swedish researchers emphasized the importance of transparent, standardized approaches to UPF classification, particularly when existing dietary surveys lack sufficient information about processing methods. They also called for improved dietary assessment tools and continued refinement of classification protocols to address uncertainty in future research.