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: 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.