The objective of this study is to determine the independent and additive effects of food texture and energy density on food and energy intake compared to a control condition.

Study design: The study has a 2x2 randomized crossover design. All participants receive 5 treatments and are their own control.

Study population: Healthy adults (n=75) between 18-55 years old with a BMI between 18.5-30 kg/m2.

Intervention: Participants will join 5 test days during which they receive, 5 test meals (lunch). The 5 test meals of this study are: 1.) low energy density, hard texture (slow eating rate) 2.) low energy density, soft texture (fast eating rate) 3.) High energy density, hard texture (slow eating rate) 4.) High energy density, soft texture (fast eating rate) 5.) Average energy density and medium hard texture (control). During eating and before and after eating the weight of the plate will be measured to determine intake. Additionally, participants will be recorded on video to determine eating behaviour (number of bites, chews and oral processing duration). The order in which participants will receive the diets will be randomized. The evening before and during each test day participants will keep a food and exercise diary.

Main study parameters/endpoints: The main study outcomes are food and energy intake of each lunch meal. Secondary outcomes are, eating behaviour characteristics measured by video (eating rate (g/min and bites/min), number of chews (chews/bite and chews/gram), bite size (gram/bite), oral processing duration (seconds), appetite (hunger, fullness, desire to eat, desire to eat sweet, desire to eat savoury, prospective consumption) and sensory characteristics (liking (taste + smell), desire to eat the meal, expected satiation, sweet, savoury, smoothness, chewiness, thickness) of the meals. Additional outcomes are individual differences in microstructure of eating, appetite responsiveness, eating Behavior phenotype, interoceptive sensitivity and anthropometry measures. During the trial new technology to capture food intake and eating behavior will be validated which is also an outcome of this trial.

Inclusion Criteria:

• Between 18-55 years old at the day of inclusion
• Able to understand and speak English fluently or without difficulty (self-report)
• BMI 18.5-30 kg/m2 - measured by the researchers at the end of information meeting
• 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 (21)
• 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 or snacks
• 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 )
• Signed up for participating in another research study
• Employee of Human Nutrition department of Wageningen university
• Thesis student or intern at the chair group of Sensory Science and Eating Behaviour Human Nutrition (WUR).
• Intensive exercising more than 8 hours per week
• Low score for liking the test foods on a nine point likert scale based on pictures of the food items.
• Unfamiliar with the test foods (self-report).

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