Abstract: Apparatus (18, 18?) is provided, which includes one or more fundic sensors (74), configured to be applied to a fundus of a subject (10), and to generate a fundic signal. The apparatus further includes a control unit (90), which is configured to make a tentative determination of ingestion by the subject (10), determine fundic impedance responsively to the fundic signal, and calculate a duration of a period during which the fundic impedance rose during the tentatively-determined ingestion. Upon finding that the duration is less than a fundic rise duration threshold value, the control unit (90) determines that the tentative determination of ingestion is a false positive. Other embodiments are also described.

Abstract: Gastric apparatus (18) is provided, including one or more sensors (70, 72, 74), adapted to generate respective sensor signals responsive to activity of a gastrointestinal tract of a subject. A control unit (90) is adapted to receive and analyze the sensor signals and to determine that an eating event has occurred, responsive to at least one of the sensor signals and a threshold. The control unit identifies an aspect of at least one of the sensor signals deriving from rhythmic activity of the gastrointestinal tract that is not indicative of current eating by the subject, and modifies the threshold responsive to the aspect of the signals that derives from activity that is not indicative of current eating. For some applications, the control unit is adapted to modify the threshold if the aspect is indicative of a migrating motor complex (MMC). Other embodiments are also described.

Abstract: A method is provided for detecting a change in posture of a subject. An electrical impedance is measured between two or more sites on a stomach (20) of the subject, and an impedance signal is generated responsive thereto. The change in posture is detected by performing a posture analysis of the impedance signal. A method is also provided for treating a subject. The method includes applying an electrical signal to a site of the subject selected from the list consisting of: a colon (402) of the subject, and a distal small intestine (408) of the subject. The signal is configured to stimulate cells of the subject to increase secretion of glucagon-like-peptide-1 (GLP-1) or PYY, or to decrease secretion of ghrelin, in order to treat the subject.