An apparatus for treating obesity and reflux disease of an obese patient has a volume filling device to be invaginated by a stomach wall portion with the outer surface of the volume filling device resting against the stomach wall, such that the volume of the food cavity is reduced in size by a volume substantially exceeding the volume of the volume filling device. An implantable movement restriction device to be invaginated by the stomach fundus wall has an outer surface to be rested against the stomach wall in a position between the patient's diaphragm and the lower part of the invaginated stomach fundus wall, such that movement of the cardiac notch of the patient's stomach towards the patient's diaphragm is restricted, to thereby prevent the cardia from sliding through the patient's diaphragm opening into the patient's thorax.
