Rationale: Several observational studies have shown that the consumption of ultra-processed foods (UPF) is associated with higher energy intake and obesity rates. However, the high eating rate of UPF might cause its high energy intake instead of the industrial processing level itself. There is a positive relationship between the eating rate and oro-sensory exposure of foods and subsequent energy intake. Food texture modifies eating rate and through that the energy intake of foods. It is shown that harder, chunkier, more viscous, and more voluminous foods decrease eating rate of foods and thus decrease energy intake. So far, research on food texture and energy intake has only been performed for one meal or one day and it is unknown if food texture and eating rate have a sustained effect on energy intake. Knowledge on the sustained effect of food texture differences could be used for strategies to drive or limit energy intake.~Objective: The primary objective is to determine the sustained effect of food texture differences (slow vs fast eating rate) of UPF on energy intake. The secondary objective is to determine the effect of texture differences (slow vs fast eating rate) of UPF on body composition changes.~Study design: The study has a randomized crossover design with two treatment arms. All participants receive both conditions (1. slow test breakfast and dinners consisting of UPF and 2. fast test breakfast and dinners consisting of UPF for twelve subsequent days) and are their own control (within subject effects).~Study population: Healthy Dutch speaking adults (n=20) between 18-55 years old with a BMI between 18.5-30 kg/m2.~Intervention: Participants will join two test periods, each consisting out of twelve days. During the test periods they will visit the eating behaviour lab where they receive ad libitum breakfast and dinner meals. During meal consumption participants are video recorded to determine eating behaviour. Standardized fixed portion lunch meals and snacks will be provided on-the-go. On weekend days participants will receive pre-packed meals. In one test period participants will receive meals consisting of UPF that have a hard texture (slow eating rate) and in the other period (randomized order) they will receive meals consisting of UPF with a soft texture (fast eating rate). The order in which participants will receive the meals within each condition will be (block) randomized.
In this study the sustained effect of food texture differences (slow vs fast eating rate) of ultra-processed foods on energy intake and body composition changes will be investigated.