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In a study of healthy adults, Virginia Tech researchers found that nutritionally matched ultraprocessed and minimally processed meals prompted different metabolic responses. Brain scans also showed differences in reward-related activity associated with how participants burned carbohydrates, though participants did not report valuing one type of food more.
Virginia Tech researchers found that healthy adults responded differently to minimally and ultraprocessed meals even when the meals were closely matched for calories and major nutrients. The study, published this month in Nature Metabolism, also linked differences in post-meal carbohydrate use with activity in brain regions involved in motivation and reward.
The study included 57 healthy adults ages 18 to 45. Participants ate both a minimally processed meal and an ultraprocessed meal in separate sessions, at least three days apart, allowing researchers to compare responses within the same people. The meals each contained 300 calories and were matched within 1 percent for carbohydrates, fat, protein, calories, water and salt, according to first author Zach Hutelin.
For metabolic testing, participants fasted overnight and ate one of the meals while researchers measured energy use in a metabolic chamber. Blood samples were collected after the meal and at six further points over three hours. Researchers reported that the ultraprocessed meal prompted a higher insulin response, blood sugar that stayed somewhat higher for longer, greater energy expenditure and less carbohydrate burning. The report does not provide numerical estimates for the size of these differences.
A group of 32 participants completed both the metabolic and brain-imaging sessions. On a separate day, they viewed food pictures during functional MRI scans and rated how much they would pay for each item. Researchers reported differences in activity in the ventral striatum and nucleus accumbens, areas involved in learning, motivation and reward. These brain responses were associated with differences in carbohydrate oxidation after the meals. Participants did not say they would pay more for either category of food.
Processing May Shape Food Responses
The findings raise the possibility that processing itself may influence the body’s response to food, beyond the calories and amounts of carbohydrate, fat and protein measured in this experiment. That could help researchers investigate how food composition and preparation relate to eating behavior and health. The study does not establish that processing causes weight gain or disease, or explain how the observed short-term responses might affect health over time.
The research addresses a question with broad relevance because ultraprocessed foods account for more than half of the average American’s daily calories, according to the report. The researchers note that these foods are often designed to be convenient, affordable and highly palatable. Observational studies have associated diets high in ultraprocessed foods with health problems, but the mechanisms behind those associations remain uncertain. This controlled meal comparison offers one possible line of investigation, not proof of a causal link to long-term outcomes.
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How Researchers Matched the Meals
Nutrition research often compares meals by their nutritional content. The Virginia Tech team asked whether meals with similar measured nutrient profiles could still prompt different responses when their level of industrial processing differed. The researchers classified foods using the Nova scale, which groups foods by processing level.
The ultraprocessed test meal included small portions of a peanut butter and jelly sandwich, deli turkey, vegetable chips, a cookie, cereal and instant mashed potatoes, with water. The minimally processed meal included banana, dried cranberries, cheese and egg. The team used these contrasting meal combinations to compare short-term metabolic measures and, in a separate session, brain responses to images of the foods. The study was led by Alex DiFeliceantonio’s lab at the Fralin Biomedical Research Institute at Virginia Tech.
“The two meals are matched within 1 percent of carbs, fat, proteins, calories, water, and salt.”
— Zach Hutelin, the study’s first author
Limits of the Short-Term Study
The results come from a small study of healthy adults and describe responses measured over a few hours after one 300-calorie meal. They do not show whether similar responses occur with other foods, in other populations, or after repeated eating over longer periods. The report also does not give the numerical size of the metabolic effects, making it difficult to judge their magnitude from the available information.
The brain-imaging results show an association between carbohydrate burning and responses to food pictures; they do not establish that one caused the other. Participants’ willingness-to-pay ratings did not differ by processing category, so the scan findings should not be treated as evidence that they consciously preferred ultraprocessed foods. It also remains unclear which features of processing—or of the particular foods and meal combinations—account for the observed differences.
Questions for Follow-Up Research
The findings point to further research on how processing changes metabolic responses and how those responses relate to brain activity and food choice. Longer studies and experiments with a wider range of matched meals could test whether the short-term differences persist and whether they help explain health outcomes associated with diets high in ultraprocessed foods.
The published report identifies potential directions for research but does not announce a follow-up trial or provide a timetable for further results. Until more evidence is available, the findings should be understood as an early comparison of short-term responses, not as a basis for a specific dietary prescription.
Key Questions
What did the study find?
Researchers reported different short-term metabolic responses after participants ate minimally processed and ultraprocessed meals matched within 1 percent for several measured nutritional characteristics. They also found brain-imaging differences associated with how participants burned carbohydrates.
Did participants prefer ultraprocessed foods?
Participants did not report that they would pay more for either the ultraprocessed or minimally processed foods. The brain-scan findings do not establish a conscious preference.
Does this prove ultraprocessed food causes diabetes?
No. The study measured short-term responses after a meal and did not test whether processing causes diabetes or other long-term health outcomes.
How large was the study?
The full study included 57 healthy adults ages 18 to 45. Of those, 32 completed both the metabolic tests and the brain-imaging sessions.
Source: hn
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