Obesity places an enormous burden on global health resources. The prevalence of obesity is increasing worldwide and of particular concern is the increasing incidence of obesity in children and adolescents that is frequently associated with diabetes and hypertension. Altered nutrition during critical periods of development can increase the risk of obesity, hypertension and cardiovascular disease in adulthood. This book outlines experiments using animal models of obesity, aimed at determining the interaction of early and late feeding state on subsequent obesity risk. The work examines both physiological and pharmacological interventions to assess the response of various brain peptides and adipose derived mediators involved in energy homeostasis in two different models of dietary obesity in the rat: overnourishment beginning immediately in the postnatal period and obesity induced in adulthood by consumption of palatable, high fat foods. The studies described in this book provide evidence of the importance of early postnatal nutrition and the consequences of consuming a high fat diet in adulthood.