Summary:
A controlled feeding and neuroimaging study from Virginia Tech reveals that industrial food processing alters human metabolism and brain reward circuitry independently of nutrient composition. Published in Nature Metabolism, the study compared meals matched within 1% for calories, carbohydrates, fats, proteins, fiber, water, and salt.
Despite identical nutritional profiles, ultraprocessed meals triggered significantly greater insulin surges, altered carbohydrate burning, and drove differential activity in the ventral striatum and nucleus accumbens during food cue evaluation.
Key Facts:
- Identical Nutrients, Divergent Metabolism: When healthy adults consumed meals matched within 1% for calories, macronutrients, sodium, and water, ultraprocessed foods triggered substantially higher insulin spikes and sustained elevated blood glucose compared to minimally processed whole foods.
- Brain Reward Modulation: Differences in post-meal carbohydrate oxidation correlated with altered neural activation patterns in the ventral striatum and nucleus accumbens, core reward and motivation hubs, when participants viewed food cues during fMRI scans.
- Beyond Macronutrient Counts: The findings provide direct biological evidence that industrial food processing methods and structural degradation disrupt metabolic regulation and brain signaling through mechanisms separate from calorie or macronutrient totals.
Source: Virginia Tech / Fralin Biomedical Research Institute at VTC
For decades, nutritional science and public dietary guidelines have operated on a foundational assumption: two meals possessing identical quantities of calories, carbohydrates, fats, and proteins will exert comparable biological impacts on systemic metabolism and blood sugar regulation.
Yet epidemiological data tells a contrasting story. Across the globe, diets dominated by ultraprocessed foods (UPFs), which now comprise more than half of daily caloric intake in the United States, consistently correlate with elevated rates of type 2 diabetes, cardiovascular disease, obesity, and depressive disorders.
A central scientific debate has divided researchers: Are ultraprocessed foods hazardous simply because they tend to be packed with added sugar, saturated fat, and salt while lacking fiber, or does the industrial degradation and chemical transformation of the food matrix itself harm human physiology?
Now, a study led by researchers at the Fralin Biomedical Research Institute at VTC at Virginia Tech provides direct experimental proof that industrial processing independently alters both metabolic kinetics and brain reward pathways.
Published in Nature Metabolism, the research shows that even when ultraprocessed and minimally processed meals are matched within 1% of every major nutritional variable, the ultraprocessed meal sparks sharper insulin responses and reprograms neural signaling in the brain’s motivational circuits.
“If you look at that population-level data, people who consume large amounts of ultraprocessed foods have higher rates of poor health outcomes, obesity, cardiac events, type 2 diabetes, and even some metrics of mental health,” said senior author Alex DiFeliceantonio, Ph.D., an associate professor at the Fralin Biomedical Research Institute and the Department of Human Nutrition, Foods, and Exercise at Virginia Tech.
“We know that the majority of ultraprocessed foods are high in fat, they’re high in sugar, they’re low in fiber, and they’re low in protein. But if we artificially hold all of those things constant, is there something about the processing that leads to a different outcome?”
Metabolic Chamber Testing: The 1% Nutritional Match
To isolate the effect of processing from nutrient content, the research team recruited 57 healthy adults aged 18 to 45, with 32 completing both metabolic chamber evaluations and functional magnetic resonance imaging (fMRI) brain scans.
Participants consumed two distinct 300-calorie test meals categorized according to the international NOVA food classification system, spaced at least three days apart following an overnight fast:
- The Highly Processed Meal (NOVA 4): A bite of a peanut butter and jelly sandwich, commercial deli turkey, processed veggie chips, a cookie, breakfast cereal, instant mashed potatoes, and water.
- The Minimally Processed Meal (NOVA 1): Fresh sliced banana, dried unsweetened cranberries, whole cheese, and hard-boiled egg.
“The two meals are matched within 1 percent of carbs, fat, proteins, calories, water, and salt,” said first author Zach Hutelin, who led the project as part of his doctoral training in Virginia Tech’s Translational Biology, Medicine, and Health Graduate Program. “If these meals had a nutritional label, they would be practically identical.”
Participants consumed the meal within a 10-minute window inside an airtight metabolic chamber, which tracks whole-body energy expenditure and respiratory exchange ratios in real time. Blood samples were drawn immediately post-consumption and six additional times across the following three hours.
The metabolic outcomes diverged immediately.
“We were shocked when every single metabolic metric differed,” Hutelin explained. “What we noticed with the ultraprocessed food is that insulin response was much higher and blood sugar stays a little bit higher for a little bit longer.”
Furthermore, while the ultraprocessed meal caused the body to expend more total energy processing the food, participants oxidized significantly less carbohydrate for fuel compared to the whole-food meal.
Neural Shifts in Reward and Motivation Circuits
Because post-ingestive nutrient sensing communicates continuously with the central nervous system via the gut-brain axis, DiFeliceantonio’s laboratory examined whether these divergent metabolic states altered brain circuits that govern eating behavior.
During separate fMRI neuroimaging sessions, participants viewed pictures of the nutritionally matched foods while evaluating their willingness to pay for each item.
The neuroimaging revealed distinct activity shifts in the ventral striatum and nucleus accumbens—critical nodes of the dopaminergic mesolimbic reward system responsible for reinforcement learning, incentive salience, and craving.
The degree to which an individual’s carbohydrate oxidation shifted following the ultraprocessed meal directly predicted differential neural responsiveness within these reward hubs when shown food images. Although participants did not express a conscious willingness to pay more for the ultraprocessed items, their reward circuits registered the metabolic discrepancies at an unconscious neurobiological level.
“A key debate in the literature is whether ultraprocessed food associations with poor health outcomes are driven by nutrient composition rather than processing,” noted Carlos A. Monteiro, M.D., Ph.D., Professor of Public Health at the University of São Paulo and creator of the NOVA classification system, who commented on the study. “This is a novel and important contribution, as the brain ultimately regulates eating behavior.”
Deconstructing the Food Matrix
The authors emphasize that because the study utilized a single 300-calorie test meal in young, healthy volunteers, broader investigations are required to assess cumulative effects across larger meals, prolonged feeding trials, and populations living with pre-existing metabolic disorders.
Future research will aim to dissect which specific components of industrial formulation drive this metabolic-neural decoupling, whether it stems from the destruction of the natural cellular food matrix, rapid gut transit and absorption rates, or synthetic emulsifiers and commercial additives.
“We want to examine specific factors, such as commercial additives or specific processing steps, that might lead to different metabolic responses,” concluded DiFeliceantonio.
Funding: The research was funded by a National Institutes of Health research grant through the National Institute of Diabetes and Digestive and Kidney Diseases and a National Science Foundation graduate research fellowship.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by our staff.
About this neuroscience and diet Research:
- Media Contact: Leigh Anne Kelley
- Source: Virginia Tech
- Image Credit: Image credited to Neuroscience News
- Original Research is Open Access: Nature Metabolism (Oct 5, 2026). “Metabolic and neural responses to ultraprocessed foods: a randomized, controlled, crossover study.” Authors: Zach Hutelin, Monica Ahrens, Mary Elizabeth Baugh, Emmanuel Nartey, Delbert L. Herald III, Alexandra L. Hanlon & Alexandra G. DiFeliceantonio.
- DOI: 10.1038/s42255-026-01619-4
Abstract
Metabolic and neural responses to ultraprocessed foods: a randomized, controlled, crossover study
Dietary patterns worldwide have shifted toward increased consumption of ultraprocessed foods (UPFs), which has been linked to higher disease burden. One proposed mechanism underlying both UPF consumption and metabolic disease is altered post-ingestive responses relative to nutritionally similar foods.
Here we report the effects of food processing on post-ingestive metabolism and brain response in a randomized, crossover study involving 57 healthy-weight adults who consumed a nutritionally matched UPF or non-UPF meal.
We show that despite being nutritionally similar, UPF meals evoke greater insulinaemic and energetic responses, with attenuated carbohydrate oxidation relative to non-UPF meals. Between-condition differences in peak carbohydrate oxidation are associated with striatal activation in response to food cues.
We also find that although subjective food value does not differ between conditions, brain responses correlated with food valuation are positive for non-UPF but negative for UPF in the visual cortex and striatum.
Overall, these findings suggest that food processing influences post-ingestive metabolic and neural responses through mechanisms beyond calories and macronutrients alone.
