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Virginia Tech researchers found that healthy adults had different metabolic responses after eating highly processed and minimally processed meals matched for key nutrients. Brain responses to food images also differed in ways linked to how participants burned carbohydrates, though they did not report valuing one type of food more.
Virginia Tech researchers report that highly processed and minimally processed meals produced different metabolic responses in healthy adults even when the meals were matched for calories, carbohydrates, fat, protein, water, salt, and weight. The study, published this month in Nature Metabolism, also found that participants’ brain responses to food images varied in ways linked to how they used carbohydrates for energy.
The study included 57 healthy adults ages 18 to 45. Each participant ate both a highly processed and a minimally processed meal in separate sessions, with at least three days between sessions. The meals each contained 300 calories and were matched within 1 percent for the listed nutritional measures. Researchers measured metabolic responses after eating; 32 participants also completed functional MRI sessions.
During metabolic testing, participants fasted overnight and ate their meal in a metabolic chamber, which measures energy expenditure and metabolism. Researchers took blood samples immediately after the meal and six more times over the next three hours. They reported that the highly processed meal prompted a larger insulin response, somewhat higher blood sugar for longer, greater energy expenditure, and less carbohydrate oxidation—meaning the body burned less carbohydrate for fuel.
On a separate day, participants viewed images of foods during brain scans and said how much they would be willing to pay for each item. The researchers found differences in activity in the ventral striatum and nucleus accumbens, brain regions involved in learning, motivation, and reward. The brain-response differences were associated with differences in carbohydrate use after the meals. Participants did not say they were willing to pay more for either category of food.
Processing May Affect More Than Nutrients
The findings suggest that nutrient labels alone may not capture every short-term response to a meal. Even with calories and major nutrients closely matched, processing level was associated with differences in insulin response, energy use, carbohydrate burning, and brain activity. That gives researchers a possible route for investigating how food characteristics relate to eating behavior and health.
The study matters against a wider public-health backdrop: the source report says ultraprocessed foods account for more than half of the average American’s daily calories, and consumption is rising in many parts of the world. Such foods are often designed to be convenient and palatable. The study does not establish that processing itself causes overeating or chronic disease, but it offers evidence that processing may be linked to body and brain responses beyond the nutrient measures controlled in this experiment.
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How Researchers Matched the Meals
Nutrition research often compares foods by their calories and amounts of carbohydrates, fat, and protein. The Virginia Tech team asked whether meals with similar measured nutritional profiles might still prompt different responses if their level of industrial processing differed. The researchers classified foods using the Nova scale, which groups foods by degree of processing.
The highly processed meal included small portions of a peanut butter and jelly sandwich, deli turkey, vegetable chips, a cookie, cereal, instant mashed potatoes, and water. The minimally processed meal included banana, dried cranberries, cheese, and egg. These were specific test meals, not a comparison of every food in either category. The design let researchers compare each participant’s responses to both meals, reducing the influence of differences between individuals.
Alex DiFeliceantonio, an associate professor at the Fralin Biomedical Research Institute at VTC, led the lab involved in the work. Zach Hutelin, a researcher at the institute and the study’s first author, conducted the project as part of his doctoral research at Virginia Tech. The team’s brain scans measured blood-flow changes, an indirect measure used to track activity across brain regions.
““The two meals are matched within 1 percent of carbs, fat, proteins, calories, water, and salt.””
— Zach Hutelin, study first author and Fralin Biomedical Research Institute researcher
Limits of the Short-Term Findings
The experiment measured responses over three hours after a single meal; it does not show whether the observed differences persist with repeated eating or lead to long-term health effects. The source report does not provide the size of each metabolic difference, so readers cannot gauge its clinical importance from the reported figures alone.
The findings also do not identify which features of processing produced the responses. Matching calories, major nutrients, water, salt, and weight helped isolate the question, but the meals still contained different foods and ingredients. Nor did participants report a greater willingness to pay for either type, leaving unclear how the measured brain differences relate to actual food choices or overeating. The study’s sample was limited to healthy adults ages 18 to 45, and only 32 of the 57 participants completed both the metabolic and brain-imaging sessions.
Further Work on Processing Effects
The study points to further research on the mechanisms that connect food processing with metabolism, brain responses, and eating behavior. Follow-up studies would need to test whether the differences recur across other matched meals, how long they last, and whether they affect real-world food intake over time.
The source report does not announce a specific next study or timetable. Until longer-term evidence is available, the results should be read as short-term findings from a controlled meal experiment, not proof that processing alone causes chronic disease or overeating.
Key Questions
What did the study find?
Participants had different metabolic responses after highly processed and minimally processed meals matched closely for calories and several major nutritional measures. Researchers also found differences in brain responses to food images associated with carbohydrate use.
Were the meals nutritionally identical?
They were not identical foods, but researchers said they were matched within 1 percent for calories, carbohydrates, fat, protein, water, and salt, as well as matched for weight.
Did participants prefer the highly processed foods?
Participants reported how much they would be willing to pay for pictured foods. The study found they did not report greater willingness to pay for either the highly processed or minimally processed options.
Does the study prove ultraprocessed foods cause disease?
No. It measured short-term responses to one meal in healthy adults. It does not establish that processing causes obesity, diabetes, or other long-term health outcomes.
Source: hn
