Eating rate has sustained effects on energy intake from ultraprocessed diets: a 2-week ad libitum dietary randomized controlled crossover trial

BACKGROUND: Previous research has shown that diets dominated by ultraprocessed foods (UPF) are associated with higher dietary energy intakes. This association may be attributable in part to meal texture and associated eating rate (ER). Experimental studies are needed to clarify the underlying mechanisms. OBJECTIVES: The objective was to compare daily energy intake (kcal/d) from diets with different meal texture-derived ER (g/min) (UPF Slow-ER compared to UPF Fast-ER) across a 14-day period. Two UPF diets comprised of foods selected to have textures known to lead to a slower or faster ER. METHODS: Forty-one participants [n = 21 male, mean (± standard deviation) age 27 ± 5; weight 70 ± 10 kg; body mass index 23.4 ± 1.9] completed a single-blind, block-randomized crossover study including 2 14-day diets; UPF Slow-ER and UPF Fast-ER, with a 2-wk washout. Diets were served ad libitum and matched for palatability, portion size served, total energy served, non-beverage energy density, and meal variety. RESULTS: Daily energy intake was 369 kcal/d (95% confidence interval: 221, 517) lower on the UPF Slow-ER diet compared with the UPF Fast-ER diet [main effect; F (1, 1051) = 23.98, P < 0.001]. The effect on energy intake was consistent across participants and the number of days on the diet [diet∗time: F (13, 1051) = 0.96, P = 0.486], and was not attributable to meal liking or macronutrient intake (all, P > 0.05). There was no change in body weight pre-diets to post-diets, and no differences in body weight between the 2 diets. Body fat mass decreased on the UPF Slow-ER diet by 0.43 kg [main effect; F (1, 119) = 14.68, P = 0.0002]. CONCLUSIONS: Food texture-derived ER has a significant and sustained effect on energy intake of ultraprocessed diets over a 2-wk period. This finding highlights the importance of food texture in guiding ER and the central role of sensory cues in regulating meal size. This trial was registered at clinicaltrials.gov as NCT06113146.