Previous reports have suggested that hypothalamic urocortin 1 (Ucn1) exerts inhibitory control on energy metabolism as direct paraventricular nucleus injections dose-dependently decrease the respiratory energy exchange ratio (RER). Other evidence indicates that Ucn1 injections into the lateral septum may alter metabolic function. Consequently, the present study was designed to further characterize the effects of lateral septal Ucn1 signaling on eating and energy metabolism of adult Sprague-Dawley rats. Ucn1 was infused at the onset of the nocturnal cycle at doses of 10 - 100 pmol. In both females and males the peptide elicited a reliable suppression of food intake and significantly lowered RER over a 4 h postinjection period. The decrease in RER is consistent with enhanced lipid oxidation. Overall these findings suggest that, similar to the paraventricular nucleus, the lateral septum is a critical site of action in mediating the effects of Ucn1 on food intake and energy substrate utilization.