Sustained Effect of Food Texture of Ultra-processed Foods on Energy Intake

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.

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.

Eligibility Criteria:
Inclusion Criteria:

* Between 18-55 years old at the day of inclusion
* Able to understand and speak Dutch and English fluently or without difficulty (self-report)
* BMI 18.5-30 kg/m2 - measured by the researchers during the information meeting (after signing informed consent)
* Good general health and appetite (self-report)
* Commonly (5 out of 7 week days) eating three meals a day every day around approximately the same times (self-report)

Exclusion Criteria:

* Difficulties with swallowing, chewing, and/or eating in general
* Suffering from an endocrine or eating disorder, gastrointestinal illness or illness of the thyroid gland, respiratory disease, or diabetes
* Having taste or smell disorders (self-report)
* Braces (not including a dental wire) or oral piercing
* Smoking
* Consuming on average more than 21 glasses of alcohol per week
* Not willing to stop using drugs during the study period (from inclusion till last test session)
* Use of medication that may influence study outcomes (self-report)
* Allergies or intolerance to any ingredient of the test meals
* Not willing to eat the test food because of eating habits, believes, or religion
* Following a vegetarian or vegan diet
* Lactose intolerant
* Men having facial hair such as a beard as facial movements cannot be analysed
* Followed an energy restricted diet during the last 2 months
* Gained or lost 5 kg of body weight over the last half year
* High restrained eater according to the Dutch Eating Behaviour Questionnaire (men: score\>2.89, women\>3.39) - this exclusion criterion will not explicitly be communicated to the participants to prevent desirable answers
* Signed up for participating in another research study of the Nutrition and Health department (WUR)
* Employee, thesis student or intern at the chair group of Sensory Science and Eating Behaviour Human Nutrition (WUR).
* Intensive exercising more than 5 hours per week
* Low score (\<1) for liking the individual test meals on a nine point Likert scale based on pictures of the meals
* Unfamiliar with the test meals (self-report)
* Having an abnormal (non-representative) eating rates - measured by the researchers during the information meeting (after signing informed consent)