Abstract
Protein sparing therapies were developed to mitigate the harms associated with protein-calorie malnutrition and nitrogen losses induced by either acute illness or hypocaloric diets in patients with obesity. We review the development of protein sparing therapies in illness and obesity with a focus on the pioneering contributions of George Blackburn, MD, PhD. He recognized that protein-calorie malnutrition is a common and serious clinical condition and developed new approaches to its treatment in hospitalized patients. His work with stable isotopes and with animal models provided answers about the physiological nutritional requirements and metabolic changes across a spectrum of conditions with varying degrees of stress and catabolism. This led to improvements in enteral and parenteral nutrition for patients with acute illness. Blackburn also demonstrated that lean body mass can be preserved during weight loss with carefully designed very low calorie treatments which became known as the protein sparing modified fast (PSMF). We review the role of the PSMF as part of the comprehensive management of obesity.