Ultra-Processed Meals Linked to Higher Insulin, and Food Images to Different Brain Reward Responses, Even When Nutrients Match

The paper, "Ultraprocessed foods evoke distinct metabolic and neural responses," was published in Nature Metabolism in 2026. We could read only the study. The study says the researchers measured acute metabolic responses to ultra-processed foods and looked at how the brain encodes food value, both nutritional and monetary. It does not give the study design, the results or the participant numbers. Those details below come from Newsweek's coverage, which describes an acute, single-meal human feeding study in just under 60 healthy adults aged 18 to 45, plus a separate brain-imaging task using food images. Whether participants were randomised is not stated in the study or the coverage we read.

According to Newsweek, participants fasted overnight and then ate one of two meals. The highly processed meal included a small piece of peanut butter and jelly sandwich, deli turkey, vegetable chips, a cookie, cereal and instant mashed potatoes. The minimally processed meal was sliced banana, dried cranberries, cheese and a hard-boiled egg. Newsweek reports the meals were matched within 1 percent for calories, carbohydrates, fats, proteins, water and salt.

Researchers then measured blood sugar and insulin several times over a few hours. Insulin is the hormone that helps move sugar from the blood into cells. Newsweek reports that the highly processed meal produced a much higher insulin response, and that blood sugar stayed elevated for longer.

Alex DiFeliceantonio, the Virginia Tech associate professor whose lab led the work, told Newsweek, "The insulin result was the most surprising to us, I didn't expect it at all." She noted that long-term ultra-processed food intake is associated with insulin resistance, and that this meal may transiently create a similar state of higher insulin.

The brain results are separate, and they did not come from eating the meals. Newsweek reports that participants, still fasted, had functional MRI scans while viewing images of both kinds of food. They were also asked whether they would pay for each food. Brain regions involved in motivation and reward responded differently to the two categories of images. DiFeliceantonio told Newsweek this suggests "the brain is encoding the value of these foods differently."

The limits matter. This was a single meal in healthy, relatively young adults. Newsweek quotes DiFeliceantonio as saying, "we don't know if these short term, immediate changes are what leads to the poor health outcomes associated with ultraprocessed foods." Dr. Dariush Mozaffarian of Tufts told Newsweek the long-term effects are "not well established." The study does not show that ultra-processed food causes disease.

The meals also contained different foods, not the same food in two forms. So this work does not test a simple swap, such as one brand of cereal for a less-processed alternative. This is the weakest point for any everyday takeaway: we cannot say whether the differences come from processing itself or from the particular foods in each meal.

What does it mean for everyday choices? Calories and macronutrients may not capture everything that matters. Mozaffarian told Newsweek the study adds to evidence that "processing matters, with effects on insulin, metabolism, and the brain beyond macronutrients alone." The study cannot yet say how much, if at all, this changes long-term metabolic health, and it offers no tested dietary advice.

Watch for follow-up studies that test repeated meals over longer periods. DiFeliceantonio said her team hopes to follow up on the insulin finding, and Dr. Lu Qi of Tulane told Newsweek that validation studies are needed.

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