We sought to determine whether an excess in energy intake as total parenteral nutrition would result in liver biochemical and histological changes in the presence of a functional gastrointestinal tract. Three groups of rats were given amounts of total parenteral nutrition that provided either 25% (total parenteral nutrition-25), 100% (total parenteral nutrition-100), or 200% (total parenteral nutrition-200) of a rat's energy requirements. Rat chow and water were available ad libitum. Food intake decreased in proportion to the amount of total parenteral nutrition infused; it ceased with total parenteral nutrition-200. Liver glycogen and triglyceride concentrations were higher with high energy intake (total parenteral nutrition-100 and total parenteral nutrition-200), while total liver nitrogen concentrations remained unchanged. No cholestasis, inflammation, or fibrosis was seen histologically. Fatty vacuoles were increased with total parenteral nutrition (more so with total parenteral nutrition-200) but a prompt return to normal liver features was observed after cessation of total parenteral nutrition and the resumption of normal food intake.