The Effect of Energy Density and Eating Rate on Ad Libitum Energy Intake in Healthy Adults-A Randomized Controlled Study

Abstract

Background: The extent to which energy density (ED) and eating rate (ER) interact in their effect on energy intake of meals remains unknown.

Objectives: The aim was to determine the independent and combined effects of ED and ER on ad libitum food and energy intake and to compare them to a control meal (medium ED and ER). We hypothesized that lower ED/slower ER would decrease intake and higher ED/faster ER would increase intake relative to control.

Methods: In a 2 x 2 randomized crossover design with a medium-control condition. Participants [n = 69, age 25 ± 5 y (mean ± standard deviation), body mass index (in kg/m²) 23 ± 4] joined 5-lunchtime meal sessions during which they were served ad libitum sandwiches (67-98 energy percentage ultra-processed ingredients) that varied in ER (slow, fast) and ED low (1.9 kcal/g), or high (3.8 kcal/g). The control meal was a "typical lunch" sandwich with medium ED (2.9 kcal/g), average ER. The main outcomes were food (grams) and energy intake (kilocalories).

Results: We found a significant ED ∗ ER interaction effect on energy intake [F ₍₁₂₇₂₎ = 5.2, P = 0.024]. Energy intake of the slow-ER/low-ED meal (mean 570 kcal; 95% confidence interval: 442, 698 kcal) was 573 kcal (50%) lower compared to the fast-ER/high-ED meal [1143 kcal; (1015, 1271 kcal)]. Compared to the control a slow-ER and low-ED reduced energy intake by 59% [mean Δ of 394 kcal; (480, 308 kcal)] and a fast-ER/high-ED increased energy intake by 19% [Δ 179 kcal; (94, 265 kcal)].

Conclusions: Our results emphasize that ED and ER can moderate ad libitum energy intake. These findings highlight the importance of combined nutrition and sensory strategies to moderate caloric intake from (ultra-processed) meals. This trial was registered at clinicaltrials.gov as NCT05659771.

Keywords: energy density; energy intake; energy intake rate; food intake; food texture.