Information about consumer welfare effects associated with quantity changes in demand is important for agricultural and food policy decision-makers because many policy options are directly related to controlling supplies as a means to stabilize or raise commodity prices and farmers’ income. A new method is developed to measure the consumer welfare effects by using the estimates of an inverse demand system and a modified quantity-adjusted Malmquist index to represent the efficiency in quantity metric welfare. The methodology is validated by applying it to a U.S. inverse food demand system consisting of 13 food groups and a nonfood sector.