Prolonged total fasting: A feast for the integrative physiologist

Adaptive strategies permit survival during an extended period without food and water. This evolution required several integrated responses to accommodate many, and seemingly conflicting, physiological demands. We believe that the setting of prolonged starvation provides an ideal opportunity to learn many lessons that will help clinicians understand integrative renal physiology, with the ultimate aim of applying new insights at the bedside. We recognize that at times speculations will take us beyond the absolute database, and these will be highlighted. In addition, new information from our own data will be provided where data are not available in the literature. Our emphasis in this review will be on how these physiologic responses might be integrated, rather than a detailed description of the different transport systems that are involved.