In this study, the investigators aimed at evaluating the role of sweet taste receptors in the gastrointestinal tract (GIT). Intragastric administration of glucose, fructose or acesulfame-K were compared with placebo administration for their effects on gastrointestinal motility, gut hormone release (motilin, ghrelin, glucagon-like peptide-1 (GLP-1) and insulin) and hunger feelings.

Inclusion Criteria:

• BMI<30 kg/m² for the lean volunteers
• Female or male subjects aged 18 to 60
• Subject is capable and willing to give informed consent
• Female volunteers of child bearing potential must use oral, injected or implanted hormonal methods of contraception

Exclusion Criteria:

• Female volunteer is pregnant or breastfeeding
• GI diseases, major abdominal surgery
• Volunteers that have food allergies, especially fructose intolerance
• Major psychiatric illnesses
• Volunteers that use drugs affecting the GI tract or the central nervous system
• Volunteers suffering from an endocrine disease such as diabetes, Cushing's disease, Addison's disease, hypothalamic tumor
• Volunteers that have undergone surgical procedure for weight loss