Effects of Ultra-Processed Meals with Differing Energy Density on Postprandial Glyco-Insulinemic and Appetite-Related Hormonal Responses: A Randomized Crossover Trial

Background/Objectives: To evaluate the metabolic and hormonal responses after meals rich in and free of ultra-processed foods (UPF), with high or low energy density (ED), in adults without obesity (body mass index [BMI] between 18.5 and 29.9 kg/m2, body fat percentage ≤ 30% for men and ≤42% for women). Methods: Randomized, crossover-controlled feeding trial. Participants were assigned to four conditions (UPF+/ED+, UPF+/ED-, UPF-/ED+, and UPF-/ED-), each receiving two standardized test meals (breakfast and lunch), matched for energy, macronutrients, fiber, saturated fat, free sugar, and sodium. Blood samples were collected after 12 h fasting, and 240 min after each meal completion for quantification of glucose, insulin, triglycerides, ghrelin, and leptin. Results: Nineteen participants (9 females; 22 y mean age; 23.5 kg/m2 mean BMI) were included. The UPF condition resulted in a statistically significant increase in postprandial circulating insulin concentrations throughout the day (p = 0.016), without interactions with meal (p = 0.09). No main effects of ED or UPF × ED interactions were observed for any outcome. Conclusions: In this exploratory secondary analysis of a randomized crossover trial, acute UPF consumption resulted in higher postprandial circulating insulin concentrations, independently of ED. These findings require confirmation in adequately powered studies. Brazilian Registry of Clinical Trials (ReBEC), registration number RBR-10gfr3fb.