Consuming an ultra-processed meal can trigger a significantly sharper spike in insulin than eating minimally processed foods with nearly identical nutritional content, according to research published in the journal Nature Metabolism.
Scientists at Virginia Tech designed an experiment to test whether industrial food manufacturing itself alters metabolic health, independent of poor nutrient profiles. While ultra-processed products are often blamed for being packed with sugar and saturated fats while lacking fiber, researchers wanted to isolate the physical processing of the food from its basic ingredients.
Identical labels, contrasting bodies
The study evaluated 57 healthy-weight adults with an average age of 26. Among them, 32 individuals took part in a randomized feeding trial across two separate days. Participants consumed two 300-calorie meals that looked strikingly different on the plate but were matched within 1 percent for calories, protein, carbohydrates, fat, salt, and water content.
The ultra-processed option included deli turkey, instant mashed potatoes, frosted wheat cereal, veggie chips, a small cookie, a bite-sized peanut butter and jelly sandwich, and water. The minimally processed meal consisted of a hard-boiled egg, sliced banana, dried cranberries, cheese, and sea salt.
“If these meals had a nutritional label, they would be practically identical,” study lead author Zach Hutelin, a biomedical researcher at Virginia Tech, said in a report from Virginia Tech News.
Researchers collected blood samples immediately after eating and six more times over the following three hours. The results revealed stark physiological differences. While both meals produced roughly similar blood sugar levels initially, glucose remained elevated for longer after the processed meal. More noticeably, insulin levels surged much higher and remained elevated for approximately two hours before declining to baseline levels.
The body also burned fuel differently. Participants who ate the ultra-processed meal experienced higher overall metabolic rates and burned more fat over three hours, but burned fewer carbohydrates compared to when they ate whole foods.
“We were shocked when every single metabolic metric differed,” Hutelin said.
Brain responses and reward circuits
In a companion experiment, participants underwent functional MRI scans to assess brain activity while looking at images of the foods and rating how much they would pay for them. Researchers discovered that neural activity in the striatum and nucleus accumbens—regions linked to motivation and reward—correlated with how participants burned carbohydrates during the meal test.
Carlos A. Monteiro, an epidemiologist at the University of São Paulo who developed the widely used NOVA food classification framework, told Nature Metabolism that linking brain responses to metabolic measurements represents a valuable step forward because brain circuits govern eating behavior.
Unanswered questions and next steps
Outside experts emphasized that the findings underline the complexity of dietary processing, but cautioned against drawing sweeping clinical conclusions. Dr. Mir Ali, medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center, told Medical News Today that the study confirmed processing alters insulin and carbohydrate metabolism, but noted it remains unclear which manufacturing methods or chemical additives cause the reaction.
Dietitian Qianzhi Jiang told Medical News Today that variations in protein sources and amino acids between the meals could also explain differences in insulin secretion. Jiang pointed out that the trial did not monitor gut hormones like GLP-1 or GIP.
Senior study author Alex DiFeliceantonio of Virginia Tech noted that future studies will need to test larger meals, evaluate older or less healthy populations, and identify whether specific commercial additives or altered physical structures are driving the metabolic shifts.
