Defecation support in elderly care presents a major burden for both caregivers and care recipients. This places additional strain related to preparation and post-processing of defecation, and stress caused by unexpected defecation. The ultimate goal of this study was to develop a system that notifies users in advance of defecation urges. Our previous studies identified changes in impedance and phase associated with defecation. In this study, we measured the abdominal impedance and phase before and after defecation to evaluate the feasibility of predicting defecation from abdominal impedance measurements. Measurements performed at several frequencies revealed increases in impedance at higher frequencies (≥ 40 kHz) and decreases in phase prior to defecation, both of which returned to baseline levels thereafter. A comparative analysis of the impedance and phase at rest and around the time of defecation confirmed that these changes were specific to the pre-defecation period. These findings suggest the potential for a non-invasive, wearable monitoring system that could alert caregivers in advance to imminent defecation, thereby reducing the burden of unexpected defecation events in elderly care.