Loss-load curves are a feedback mechanism for rate-based congestion control in packet-switched networks. The novel feature of loss-load curves is that they provide a direct mathematical relationship between offered load and the level of packet loss within the network. With this feedback information, traffic sources can dynamically compete for and share the available bandwidth on a network. Sources can use loss-load curve information to maximize raw throughput, to optimize file transfer response time, or to control end-to-end packet loss within the network. The focus of this paper is on the mathematical underpinnings of the loss-load model. The paper presents three key theoretical results for the loss-load model, and then discusses the advantages and disadvantages of the loss-load approach to dynamic bandwidth allocation. Formal proofs of the theoretical results are given.