This is a pilot dose-finding study, which is performed with a randomized, double-blind, 3-armed, unbalanced, cross-over study design. Three of four different doses of L-lysine Monohydrate (A = 0.5 g, B = 1.2 g, C = 3.0 g and D = 7.5 g) will be applied in a randomized sequence on three different study days in six healthy volunteers. Each study day involves the repeated measurement of gastric content volume, gastric secretion volume and intestinal fluid volume using MRI before and after intragastric infusion of L-lysine Monohydrate test meals. Additionally, symptoms for hunger, fullness, nausea, bloating, abdominal cramps and urge to defecate will be recorded using a scale from 0-10. In parallel, samples of gastric juice to measure intragastric pH and pepsin concentration, samples of venous blood to assess blood pH and haematocrit as well as L-lysine, Serotonin, chloride bicarbonate and albumin plasma concentration and samples of arterialized blood from ear lobe to measure glucose blood concentration will be collected