An apparatus for treating obesity and reflux disease of an obese patient having a stomach with a food cavity, the apparatus comprising: an implantable movement restriction device adapted to be at least partly invaginated by the patient's stomach fundus wall and having an outer surface that includes a biocompatible material, wherein a substantial part of the outer surface of the movement restriction device is adapted to rest against the stomach wall, without injuring the latter, in a position between the patient's diaphragm and at least a portion of 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, when the movement restriction device is invaginated, to thereby prevent the cardia from sliding through the patient's diaphragm opening into the patient's thorax, so as to maintain the supporting pressure against the patient's cardia sphincter muscle exerted from the patient's abdomen, the movement restriction device having a size of at least 125 mm 3 and a circumference of at least 15 mm when implanted, and characterised by further comprising at least one volume filling device having a maximum circumference of at least 30 millimetres and being adapted to be invaginated by a stomach wall portion of the patient and having an outer surface that includes a biocompatible material, wherein the volume filling device is adapted to be placed with the outer surface 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, when implanted. an implantable movement restriction device adapted to be at least partly invaginated by the patient's stomach fundus wall and having an outer surface that includes a biocompatible material, wherein a substantial part of the outer surface of the movement restriction device is adapted to rest against the stomach wall, without injuring the latter, in a position between the patient's diaphragm and at least a portion of 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, when the movement restriction device is invaginated, to thereby prevent the cardia from sliding through the patient's diaphragm opening into the patient's thorax, so as to maintain the supporting pressure against the patient's cardia sphincter muscle exerted from the patient's abdomen, the movement restriction device having a size of at least 125 mm 3 and a circumference of at least 15 mm when implanted, and characterised by further comprising at least one volume filling device having a maximum circumference of at least 30 millimetres and being adapted to be invaginated by a stomach wall portion of the patient and having an outer surface that includes a biocompatible material, wherein the volume filling device is adapted to be placed with the outer surface 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, when implanted.