A muscle stimulation device has a control unit (1) that determines frequency and/or intensity of electrical impulses in dependence upon the degree of stomach filling. The impulses function to stimulate lower esophageal sphincter (11) by means of stimulating electrodes (5a, 5b, 5c) disposed radially around the sphincter (11). A computer program, executable by means of a microprocessor (10), is installed in the control unit, the program designed such that a higher stomach filling degree causes a stronger stimulation of the sphincter (11) or its substitute. The sphincter reacts to the stimulation by exerting a corresponding pressure onto a lower esophagus area (12). An increased risk of gastric reflux as a consequence of the patient's substantial food ingestion is countered by an increased stimulation of the sphincter, which in turn causes an elevated closing pressure at the lower esophagus (12). When the stomach is empty or nearly empty, the closing pressure is correspondingly reduced and the food ingestion is facilitated.