Rats exposed to repeated restraint (RR) lose weight and do not return to the weight of nonstressed controls (CTRL). This study tested the effect of corticosterone (cort) on sustained weight loss by subjecting intact, adrenalectomized (ADX) and ADX with cort replacement (ADX CORT) rats to RR. RR ADX CORT rats had the same initial and sustained weight loss asRR intact rats. CTRL ADX CORT and RR ADX rats lost half as much weight and maintained the weight loss for less time than RR intact. Thus both stress-induced cort and an undefined aspect of RR are required for sustained weight loss. In a second set of rats, PVN CRF mRNA expression was increased in ADX and RR rats compared with CTRL intact rats. Cort did not inhibit expression in ADX rats. This suggests that cort contributes to initial and sustained weight loss in RR rats independent of PVN CRF mRNA.