(P04-008-25) Impact of Decreasing Ultra-Processed Food Intake on Whole-Body Metabolism

Objectives: The Western diet is rich in ultra-processed foods (UPF) and this may be partially driving the prevalence of obesity and cardiometabolic disease. Little is known about the benefits of aiming to decrease UPF intake in free-living contexts, particularly when examining whole-body metabolism. This study aims to identify the potential benefits of striving to consume a low-UPF diet on substrate oxidation in humans.

Methods: As part of an ongoing trial, 26 participants (n = 13 males, n = 13 females; age 36.1 ± 10.9 years; BMI 30.8 ± 7.5 kg/m2) were instructed to consume a minimally processed diet for 6 months. Participants completed 3-day diet records before and after the intervention. Diet records were entered into ESHA Food Processor for analysis and individual foods coded manually based on NOVA Food Classification Category. Percent calories from UPF were computed. Fasting resting metabolic rate was measured using indirect calorimetry with a canopy hood connected to a metabolic analysis system (Parvo Medics TrueOne 2400) before and after the intervention.

Results: Participants significantly decreased the percentage of UPF in their diet from baseline (62.0 ± 28.1 %) to 6 months (40.2 ± 25.6 %; p < 0.0001). Resting energy expenditure (REE) did not change significantly from baseline (1764 ± 378 kcal) to 6 months (1768 ± 382 kcal; p = 0.708). There was a significant decrease in the respiratory quotient (RQ) from baseline (0.80 ± 0.08) to 6 months (0.75 ± 0.04; p = 0.005), reflecting a significant increase in resting fat oxidation from baseline (66.2 ± 26.3 %) to 6 months (83.6 ± 13.0 %). Accordingly, carbohydrate oxidation at rest significantly decreased from baseline (34.1 ± 26.5 %) to 6 months (16.7 ± 13.1 %). There was no correlation between change in UPF intake and change in REE (r = 0.064; p = 0.756). However, there was a marginal positive correlation between change in UPF intake and change in RQ (r = 0.263; p = 0.069), indicating that as UPF intake decreased, RQ tended to decrease.

Conclusions: Despite not seeing a change in REE, when people decreased their intake of UPF there was a significant decrease in RQ, indicating greater fat oxidation and less carbohydrate oxidation. This shift may provide positive cardiometabolic and bioenergetic benefits, but this will need to be further explored

Funding Sources: USDA NIFA AFRI Seed Grant (2023-69015-39600)