LEP and obesity disorder: In addition, Levin et al. reported that offspring from Sprague–Dawley rat dams predisposed to obesity (DIO) were more sensitive to diet-induced obesity with elevated leptin and plasma glucose levels than those from obese-resistant dams (DR) when the dams were challenged with a high-fat diet (HFD) (Levin et al. 1997, Levin & Govek 1998).