A system for locating an intragastric device inside the body, the system comprising: an electromagnetic field generator for generating a magnetic field; a sensor interface unit; a system control unit in electrical communication with the sensor interface unit and the electromagnetic field generator; a computer in electrical communication with the system control unit; a volume occupying intragastric device configured to be positioned in an in vivo gastric environment in use, the volume occupying intragastric device having a valve system, wherein the volume occupying intragastric device is a swallowable balloon capsule; a swallowable catheter configured to releasably couple with the intragastric device via the valve system to introduce an initial fill fluid into the volume of the occupying intragastric device in use; an electromagnetic sensor configured to couple with the volume occupying device or the swallowable catheter and further configured to: produce an electric current when exposed to the magnetic field; create an electrical signal in response to this current that is detected and transmitted to the system interface unit, a voltage sensor arranged to provide confirmation that the intragastric device is in a stomach; wherein: the sensor interface unit is configured to transmit a signal to the system control unit in response to receiving the electrical signal from the electromagnetic sensor, the system control unit configured to calculate a position and orientation of the electromagnetic sensor based upon the signal from the sensor interface unit; the system control unit is configured to transmit a signal to the computer; and the computer comprises a display configured to show identifiers for indicating a location of the electromagnetic sensor in use; the voltage sensor comprises: an integrated circuit coupled with the volume occupying intragastric device and comprising a battery constructed on a surface of the circuit, the battery being configured to be powered when the integrated circuit is exposed to stomach fluid as an electrolyte; and a body mounted receiver for communication with an external device, and the integrated circuit is configured to communicate with the receiver only when the battery is powered such that the receiver is configured to communicate with the external device to indicate that the volume occupying intragastric device is inside the stomach; and the integrated circuit is configured to separate from the intragastric device in the stomach after having communicated with the receiver. an electromagnetic field generator for generating a magnetic field; a sensor interface unit; a system control unit in electrical communication with the sensor interface unit and the electromagnetic field generator; a computer in electrical communication with the system control unit; a volume occupying intragastric device configured to be positioned in an in vivo gastric environment in use, the volume occupying intragastric device having a valve system, wherein the volume occupying intragastric device is a swallowable balloon capsule; a swallowable catheter configured to releasably couple with the intragastric device via the valve system to introduce an initial fill fluid into the volume of the occupying intragastric device in use; an electromagnetic sensor configured to couple with the volume occupying device or the swallowable catheter and further configured to: produce an electric current when exposed to the magnetic field; create an electrical signal in response to this current that is detected and transmitted to the system interface unit, produce an electric current when exposed to the magnetic field; create an electrical signal in response to this current that is detected and transmitted to the system interface unit, a voltage sensor arranged to provide confirmation that the intragastric device is in a stomach; the sensor interface unit is configured to transmit a signal to the system control unit in response to receiving the electrical signal from the electromagnetic sensor, the system control unit configured to calculate a position and orientation of the electromagnetic sensor based upon the signal from the sensor interface unit; the system control unit is configured to transmit a signal to the computer; and the computer comprises a display configured to show identifiers for indicating a location of the electromagnetic sensor in use; the voltage sensor comprises: an integrated circuit coupled with the volume occupying intragastric device and comprising a battery constructed on a surface of the circuit, the battery being configured to be powered when the integrated circuit is exposed to stomach fluid as an electrolyte; and a body mounted receiver for communication with an external device, and an integrated circuit coupled with the volume occupying intragastric device and comprising a battery constructed on a surface of the circuit, the battery being configured to be powered when the integrated circuit is exposed to stomach fluid as an electrolyte; and a body mounted receiver for communication with an external device, and the integrated circuit is configured to communicate with the receiver only when the battery is powered such that the receiver is configured to communicate with the external device to indicate that the volume occupying intragastric device is inside the stomach; and the integrated circuit is configured to separate from the intragastric device in the stomach after having communicated with the receiver.