A method and apparatus for determining gastric content volume. The internal temperature of the contents of the stomach is measured at least one predetermined time t after the patient is fed, and the gastric volume determined from the temperature. In preferred embodiments, a known volume of water at a known temperature is injected into the stomach, and the temperature of the stomach contents is measured after the stomach temperature has stabilized. An apparatus for performing the method, in which continuous measurement is possible without disturbing the patient's feeding schedule, and a method for using the inventive method in the control of an automatic feeding apparatus, are also disclosed.
