To date, very little is known about the pathophysiology of Idiopathic Feline Hepatic Lipidosis (IHL). Anorexia, weight loss, icterus, and elevated serum activities have commonly been associated with IHL. Studies of a spontaneous outbreak of IHL in a group of laboratory cats engaged in a nutrition study in a cat colony indicated that fasting obese cats induces hepatic lipidosis (HL). Usual serum liver parameters are very late indicators of HL, but they are good tools for objective assessment of recovery. Hepatic lipidosis produced by fasting obese cats may be a valuable tool in investigating the pathophysiology and treatments of IHL.