In 57 adults, an ultraprocessed meal raised insulin response more than a nutritionally matched one

According to nature.com, a randomized crossover study published on 5 October in Nature Metabolism compared the body's response to ultraprocessed (UPF) and non-UPF meals matched for nutrition. The full study included 57 healthy-weight adults. Of these, 32 completed both metabolic sessions and 52 completed a functional magnetic resonance imaging (fMRI) session nature.comnature.comnature.comOpen source ↗.

Participants ate a meal of about 300 kcal made entirely of either UPF or non-UPF food and had to finish it within 10 minutes. Processing level was defined by the Nova classification. The authors note that higher UPF intake is associated with cancer, overweight and obesity, and metabolic dysfunction, but the mechanism is not fully established. They tested whether altered post-ingestive responses could be one such mechanism.

Metabolic response

The meals were matched for energy and for carbohydrate, fat, protein, fibre, water and salt content. Even so, UPF meals evoked greater insulinaemic and energetic responses than non-UPF meals. Carbohydrate oxidation was attenuated after the UPF meal relative to the non-UPF meal. After the non-UPF meal, the rise in carbohydrate oxidation was more pronounced.

Brain response and sample

Between-condition differences in peak carbohydrate oxidation were associated with striatal activation in response to food cues nature.comnature.comnature.comOpen source ↗. Subjective food value did not differ between conditions. However, brain responses correlated with food valuation were positive for non-UPF and negative for UPF in the visual cortex and striatum.

The sample was 31.6% male, with a mean age of 26.21 ± 6.85 years and a body mass index of 22.75 ± 1.87 kg m−2. Habitual energy intake of participants was on average 54.4 ± 18.4% UPF, close to the national average of 55.0% cited by the authors.

The authors conclude that food processing influences post-ingestive metabolic and neural responses through mechanisms beyond calories and macronutrients alone.