The papers in this volume were presented at a conference entitled Nutritional Implications of Macronutrient Substitutes held by the New York Academy of Sciences Institute and the International Life Sciences Institute North America Technical Committee on Macronutrient Substitution, on October 27-29 1996, in Arlington, Virginia, USA. The focus of the volume is on the understanding of the impact of macronutrient substitutes on energy and nutrient intake, food selection, and dietary patterns. Currently, Americans are eating numerous lower fat and sugar-free foods, which are made possible by the technology of macronutrient substitutes. These include the intense sweetners and fat replacers, of which the carbohydrate and protein type are available. As a major reason for the initial development of macronutrient substitutes was the increase in obesity in the population of the United States, this volume discusses the energy balance.