Overview
- The peer‑reviewed experiment published Monday in Nature Metabolism tested 57 healthy adults and used a randomized crossover design with 32 participants completing both metabolic chamber measurements and fMRI scans.
- Participants ate two 300‑calorie meals matched within 1% for calories, macronutrients, fiber, water, and salt with one meal classified as ultraprocessed under the NOVA system and the other as minimally processed.
- The ultraprocessed meal produced substantially higher insulin responses, greater post‑meal energy expenditure, and a reduced shift toward carbohydrate oxidation compared with the matched minimally processed meal.
- Differences in metabolism tracked with altered activity in the brain’s reward hubs, including the ventral striatum and nucleus accumbens, even though participants did not report higher conscious valuation for ultraprocessed items.
- Authors and commentators say the results offer controlled mechanistic evidence that processing itself matters but note the study tests only a single small meal in young healthy adults and call for work to identify causal processing features and test larger, longer, and clinical‑population studies.