Study finds ultraprocessed foods trigger distinct metabolic and brain responses

For decades, nutritionists have operated from a straightforward assumption: if two meals contain the same calories, carbohydrates, fats, and proteins, they should affect your body in roughly the same way. A Virginia Tech research team set out to test that premise and found it was wrong.

The researchers recruited 57 healthy adults and had them eat two meals that were nutritionally identical on paper. One meal was minimally processed—a sliced banana, dried cranberries, cheese, and an egg. The other was heavily processed—a peanut butter and jelly sandwich, deli turkey, veggie chips, a cookie, instant mashed potatoes, and cereal. The two meals matched within one percent on calories, carbohydrates, fat, protein, water, and salt. If you'd looked at their nutrition labels, they would have been practically indistinguishable. Yet when the researchers measured what happened inside the participants' bodies, nearly everything differed.

After eating the ultraprocessed meal, participants' bodies released significantly more insulin and their blood sugar remained elevated longer than after the minimally processed meal. They also burned less carbohydrate for fuel and expended more total energy. These metabolic shifts matter because chronically elevated blood sugar increases the risk of diabetes and other metabolic diseases. The findings, published October 5 in Nature Metabolism, suggest that something about the processing itself—beyond the basic nutritional content—changes how the body responds to food.

The research team, led by associate professor Alex DiFeliceantonio at the Fralin Biomedical Research Institute, also examined what happened in the brain. On a separate day, participants viewed pictures of processed and minimally processed foods while undergoing functional MRI scans that tracked blood flow and neural activity. They were asked how much they would be willing to pay for each food. The scans revealed differences in activity within the ventral striatum and nucleus accumbens, regions involved in motivation, learning, and reward. Notably, the differences in how participants' brains responded to food images were linked to the metabolic differences their bodies had shown after eating the meals. The participants didn't consciously report wanting to pay more for the ultraprocessed foods, yet their brains showed distinct patterns of activation tied directly to how their metabolism had reacted.

This connection between metabolism and brain response may help explain a persistent puzzle in nutrition science: why ultraprocessed foods, which now make up more than half of the average American's daily calories, are so strongly associated with overconsumption and poor health outcomes. DiFeliceantonio noted that people who consume large amounts of ultraprocessed foods have higher rates of obesity, heart disease, type 2 diabetes, and even certain mental health problems. The mechanisms driving these associations have remained unclear, especially since researchers could point to high sugar, high fat, and low fiber content as culprits. But this study suggests the processing itself matters in ways that go beyond those basic nutrients.

The work has clear limitations. The study examined only one pair of matched meals at 300 calories each, and all participants were young and healthy. The minimally and highly processed meals differed not just in processing but in their specific ingredients—the protein sources were different, for instance, and the ultraprocessed meal contained more commercial additives. The researchers did not explicitly measure the physical and chemical structures of the foods, which could have influenced outcomes. DiFeliceantonio said the next phase of research will test different populations, longer time periods, larger meals, and more pairings of foods. She wants to isolate specific factors—particular additives, specific processing steps, the structural changes that occur during manufacturing—that might drive the metabolic differences they observed.

The findings arrive at a moment when ultraprocessed foods are becoming more prevalent globally, engineered to be convenient, affordable, and highly palatable. Understanding why processing itself changes how bodies and brains respond to food could reshape how public health officials approach diet and disease prevention. It also opens a new frontier for nutrition research: moving beyond counting nutrients to understanding how industrial food manufacturing alters the fundamental way human physiology engages with what we eat.