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In a study published in Nature Metabolism, Virginia Tech researchers found that healthy adults had different metabolic responses after eating minimally and ultraprocessed meals matched for key nutritional measures. Brain scans also showed processing-related differences in responses to food images, although participants did not report valuing either type of food more highly.
Virginia Tech researchers report that minimally and ultraprocessed meals matched for calories and major nutrients prompted different metabolic responses in healthy adults, with brain scans also showing differences in responses to food cues. The study, published this month in Nature Metabolism, suggests food processing may matter to the body and brain beyond the meals’ measured content of carbohydrates, fat, protein, water, salt and calories; it does not establish that processing itself causes long-term disease.
The study included 57 healthy adults aged 18 to 45. Participants ate both a minimally processed meal and a highly processed meal in separate sessions, with at least three days between them. The meal comparison was designed to hold major nutritional measures steady: researcher Zach Hutelin said the meals were matched within 1 percent for calories, carbohydrates, fat, protein, water and salt.
The meals were not identical in ingredients. The ultraprocessed selection included portions of a peanut butter and jelly sandwich, deli turkey, vegetable chips, a cookie, cereal and instant mashed potatoes. The minimally processed meal included banana, dried cranberries, cheese and egg. Each meal contained 300 calories and was eaten within 10 minutes after participants had fasted overnight.
For the metabolic tests, researchers used an airtight chamber to measure energy expenditure and metabolism. They took blood samples after the meal and at six further points over three hours. The team reported higher insulin response and slightly higher blood sugar for longer after the ultraprocessed meal. Participants also expended more energy and burned less carbohydrate for fuel after that meal, according to the report. The researchers said every measured metabolic metric differed, though the source does not give numerical effect sizes.
A subset of 32 participants also completed functional MRI sessions on a separate day. While viewing images of foods, participants said how much they would be willing to pay for them. The researchers reported differences in activity in the ventral striatum and nucleus accumbens, regions involved in learning, motivation and reward. The brain response differences were linked to differences in carbohydrate use after the meals. Participants did not report being willing to pay more for either food category.
Processing May Alter Meal Responses
The findings address a gap in research on ultraprocessed foods. Such foods are often high in fat and sugar and low in fiber and protein, making it difficult to separate the effects of processing from differences in nutritional composition. By matching meals on several measured properties, this study offers evidence that responses may differ even when those measures are similar.
That matters because ultraprocessed foods account for more than half of the average American’s daily calories, according to the report, and their share of diets is rising globally. Population studies have associated diets high in these foods with poorer health outcomes, but this experiment does not show that the meals caused obesity, diabetes, heart disease or mental-health conditions. Instead, the metabolic and brain findings point to possible mechanisms for further study, including whether different responses affect eating patterns over time.
The results also caution against treating a nutrition label as a complete account of how a meal affects the body. Matching calories and listed nutrients did not produce matching short-term responses in this small study. It remains unknown which aspects of processing, ingredients or meal structure account for the differences.
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How Researchers Matched the Meals
Food-processing research often relies on the Nova scale, which groups foods by degree of industrial processing. The Virginia Tech team used that framework to select minimally and highly processed meals, then matched the meals on calories and several other nutritional measures. The experiment was designed to investigate whether processing could be associated with a different response when those measured factors were held close.
The study used a within-participant design: each person ate both meal types, allowing researchers to compare responses in the same individual rather than only between separate groups. Metabolic measurements followed a controlled, short-term meal test, while the functional MRI task assessed brain responses to food pictures. These methods capture immediate physiological and brain signals; they do not track what participants ate over months or years.
Alex DiFeliceantonio, an associate professor at the Fralin Biomedical Research Institute at VTC, led the lab behind the study. The research was also part of first author Zach Hutelin’s doctoral work in Virginia Tech’s Translational Biology, Medicine, and Health Graduate Program. The team’s report was published in Nature Metabolism in October 2026.
“The two meals are matched within 1 percent of carbs, fat, proteins, calories, water, and salt.”
— Zach Hutelin, the study’s first author and a researcher at the Fralin Biomedical Research Institute
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What the Meal Test Cannot Show
The study establishes short-term differences in measured responses under its testing conditions, but it does not determine whether those differences persist with repeated eating or affect long-term health. The source does not provide the size of the reported effects, detailed results for each metabolic measure, or enough information to judge how well the findings apply beyond healthy adults aged 18 to 45.
It is also unclear what features of the meals drove the differences. Matching calories, macronutrients, water and salt does not make foods identical in every respect. Ingredients, food structure and other characteristics may have differed alongside processing. The brain-imaging results show associations between metabolic differences and responses to food images; they do not establish that one caused the other. Participants’ stated willingness to pay also did not differ by processing level, so the scan findings should not be read as proof that ultraprocessed foods were more rewarding to them.
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Further Tests of Processing Effects
The results point to further research on which food characteristics produce the metabolic and brain-response differences, and whether those responses recur in larger or more varied groups. Longer studies could examine whether short-term changes have any relationship to eating behavior or health over time; this experiment alone cannot answer that.
The supplied report does not announce a follow-up study or a timetable for additional results. For now, the finding is evidence of distinct responses to two carefully matched meals, not a basis for assigning long-term effects to processing alone.
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Key Questions
What did the Virginia Tech study find?
Researchers reported that healthy adults had different short-term metabolic responses after eating minimally and ultraprocessed meals matched for calories and several major nutritional measures. Brain scans also showed different responses to food images, associated with differences in carbohydrate use.
Were the two meals nutritionally identical?
No. They were matched within 1 percent for calories, carbohydrates, fat, protein, water and salt, but they contained different foods and were not identical in every characteristic. The study tested meals designed to be closely matched on those specific measures.
Does this study prove ultraprocessed foods cause diabetes or heart disease?
No. The experiment measured responses over a few hours after a meal. It did not test long-term disease outcomes or prove that processing caused them. The report notes that population research has associated high consumption of ultraprocessed foods with poorer health outcomes, but association is not proof of cause.
Did participants prefer ultraprocessed foods?
Participants did not say they were willing to pay more for either the ultraprocessed or minimally processed foods. The brain scans showed differences in responses to food pictures, but those findings do not establish a stated preference for one category.
What remains unknown?
Researchers have not established which characteristics of the meals drove the differences, whether the responses persist with repeated eating, or whether they influence long-term health. The report also does not give numerical effect sizes for the metabolic findings.
Source: hn
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