The potential lipotoxic effect of accumulation of fatty acids in non-adipose tissues is thought to be a major component in the development of insulin resistance. Chronic exposure to high concentrations of free fatty acids in the blood affects pancreatic ß cell function, insulin secretion and lipid synthesis in the liver, and storage in adipose tissue. Maintaining the normal levels of fatty acids requires coordinated regulation between the liver, adipose tissue and skeletal muscle. This book deals with the molecular aspects of fatty acid action in obesity and insulin resistance. The topics include lipid metabolism and adipose tissue biology, and ß cell function and insulin resistance. Chapters deal with the molecular genetics and molecular physiology of energy homeostasis.