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

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

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.

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).

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)].

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.