Interaction of fat with the mouth, stomach and intestine will trigger physiological responses that will impact on the digestion, gut transit time and absorption of fat. These responses will also influence and contribute to regulation of food intake and satiety. No systematic research on understanding how the physiological-chemical properties of food affect the digestion and absorption of lipids has been carried out previously. Studies have shown that the release of free fatty acids triggers the fat-related responses. The investigators hypothesize that the release of fatty acids depends on the colloidal state of the fat, which changes progressively due to the pH changes and enzyme activities in the mouth, stomach and intestine.

Inclusion Criteria:

1. Signed informed consent form
2. Sex: male or female
3. Age: 18-55 years
4. Body Mass Index (BMI): 18-29 kg/m2
5. Based on medical history and previous examination, no gastrointestinal complaints can be defined.

Exclusion Criteria:

1. Evidence 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
2. Gastrointestinal or hepatic disorders influencing gastrointestinal absorption or transit
3. Use of psychotropic drugs, including: benzodiazepines. Concomitant medication that can increase gastric pH (e.g. antacids, proton pump inhibitors, prostaglandins, anticholinergic agents, H2-receptor antagonists), or alter gastric emptying (e.g. metoclopramide, cisapride, domperidone and erythromycin, anticholinergics, tricyclic antidepressants, narcotic analgetics, adrenergic agents, calcium channel blockers), or alter intestinal transit (e.g., loperamide, chemical/osmotic/bulk laxatives) or influence satiety/energy intake (e.g. sibutramine, glucocorticoids, anabolic steroids), except oral contraceptives
4. Pregnancy, lactation, wish to become pregnant during study, or having a positive pregnancy test at inclusion
5. Reported unexplained weight loss/gain of more than 2 kg in the month before the study enrollment
6. Score > 9 on Factor 1 (dietary restrained) of the Dutch translation of the Three Factor eating Questionnaire (TFEQ) [17]
7. Blood donations less than three months previous to study enrollment, and for three months following participation
8. One or more of the following dietary habits: medically prescribed diets, weight reduction diets, or vegetarian/macrobiotic/biologically dynamic food habits. Administration of investigational drugs in the 180 days prior to the study
9. Major abdominal surgery interfering with gastrointestinal function (uncomplicated appendectomy, cholecystectomy and hysterectomy allowed, and other surgery upon judgement of the principle investigator)
10. Premenstrual syndrome, dieting (medically prescribed, vegetarian, diabetic, biological dynamic)
11. Excessive alcohol consumption (>20 alcoholic consumptions per week)
12. Smoking
13. Self-admitted HIV-positive state