Even With Identical Nutrients, Ultraprocessed Food Raised Insulin More: A 57-Person Crossover Trial
Even meals matched for calories and nutrients produced different post-meal metabolic and brain responses depending on how processed they were.
Even when calories and nutrient composition were matched exactly, meals made of ultraprocessed food (UPF) produced different responses in the body from meals that were not. Researchers at Virginia Tech in the United States published in Nature Metabolism the results of a randomised controlled crossover study of 57 normal-weight adults.
Each person ate both meals for comparison
Participants ate a nutritionally matched UPF meal and a non-UPF meal, and the researchers measured the post-meal insulin response, energy expenditure, carbohydrate oxidation rate and brain responses when viewing food cues. After the UPF meal, insulin and energy responses were larger and carbohydrate oxidation was lower. The difference in peak carbohydrate oxidation rate between the two conditions was associated with how strongly the striatum, part of the reward circuit, responded to food cues.
The value that participants themselves assigned to the foods did not differ between the two meals. However, visual cortex and striatum responses linked to evaluating food value went in a positive direction after the non-UPF meal and in a negative direction after the UPF meal. The researchers interpreted this to mean that processing itself, apart from calories and nutrients, affects post-meal metabolism and brain responses.
Because the study looked at short-term meal responses in normal-weight adults, it cannot be extended to long-term weight change or disease outcomes. The abstract gives no specific effect sizes.
- 57 normal-weight adults, randomised crossover comparison of a nutritionally matched UPF meal and a non-UPF meal
- After the UPF meal, insulin and energy responses were larger and carbohydrate oxidation was lower
- Subjective preference was the same, but the direction of brain responses tied to food value evaluation was opposite in the two meals
Limitations A study of short-term responses after a single meal; long-term effects on weight or disease and effect sizes cannot be known from the abstract alone.
Original research
- Hutelin Z, et al. · Virginia Tech (Fralin Biomedical Research Institute). Metabolic and neural responses to ultraprocessed foods: a randomized, controlled, crossover study. Nature Metabolism. DOI: 10.1038/s42255-026-01619-4
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