Metabolic and neural responses to ultraprocessed foods: a randomized, controlled, crossover study.

Dietary patterns worldwide have shifted toward increased consumption of ultraprocessed foods (UPFs), which has been linked to higher disease burden. One proposed mechanism underlying both UPF consumption and metabolic disease is altered post-ingestive responses relative to nutritionally similar foods. Here we report the effects of food processing on post-ingestive metabolism and brain response in a randomized, crossover study involving 57 healthy-weight adults who consumed a nutritionally matched UPF or non-UPF meal. We show that despite being nutritionally similar, UPF meals evoke greater insulinaemic and energetic responses, with attenuated carbohydrate oxidation relative to non-UPF meals. Between-condition differences in peak carbohydrate oxidation are associated with striatal activation in response to food cues. We also find that although subjective food value does not differ between conditions, brain responses correlated with food valuation are positive for non-UPF but negative for UPF in the visual cortex and striatum. Overall, these findings suggest that food processing influences post-ingestive metabolic and neural responses through mechanisms beyond calories and macronutrients alone.