The appearance of intact macronutrients in the small intestine induces an intestinal brake; a negative feedback mechanism from different parts of the intestine to the stomach, the small intestine and to the central nervous system. These processes inhibit food processing, appetite sensations and food intake, and furthermore they increase feelings of satiety and satiation. Several studies showed that intraileal infusion of nutrients resulted in a reduction in food intake. However only acute effects were investigated in these studies and thus far it is not known whether repetitive (intermittent) infusion results in adaptation to repeated exposure and, thus, a lowered ileal brake response.

Inclusion Criteria:

• Based on medical history and previous examination, no gastrointestinal complaints can be defined.
• Age between 18 and 65 years. A higher age comes with a higher chance of comorbidities. These could influence our study outcomes and therefore this age range was chosen. Furthermore, we think this study would be too invasive for subjects over the age of 65. This study will include healthy adult subjects (male and female). Women must be taking contraceptives.
• BMI between 18 and 25 kg/m2)
• Weight stable over at least the last 6 months (≤5% weight change)

Exclusion Criteria:

• History of severe cardiovascular, respiratory, urogenital, gastrointestinal/ hepatic, hematological/immunologic, HEENT (head, ears, eyes, nose, throat), dermatological/connective tissue, musculoskeletal, metabolic/nutritional, endocrine, neurological/psychiatric diseases, allergy, major surgery and/or laboratory assessments which might limit participation in or completion of the study protocol. The severity of the disease (major interference with the execution of the experiment or potential influence on the study outcomes) will be decided by the principal investigator.
• Use of medication, including vitamin supplementation, except oral contraceptives, within 14 days prior to testing
• Administration of investigational drugs or participation in any scientific intervention study which may interfere with this study (to be decided by the principle investigator), in the 180 days prior to the study
• Major abdominal surgery interfering with gastrointestinal function (uncomplicated appendectomy, cholecystectomy and hysterectomy allowed, and other surgery upon judgement of the principle investigator)
• Dieting (medically prescribed, vegetarian, diabetic, macrobiological, biological dynamic)
• Pregnancy, lactation
• Excessive alcohol consumption (>20 alcoholic consumptions per week)
• Smoking
• Blood donation within 3 months before the study period
• Self-admitted HIV-positive state
• Evidence of casein or hypersensitivity