Lorcaserin is a selective 5-hydroxytryptamine receptor 2c agonist developed as a weight-loss drug. Phase II and III clinical trials support lorcaserin as not only reducing adiposity (i.e., fat mass), but also as improving the metabolic diseases commonly associated with adiposopathy (i.e., fat dysfunction). At the time of this writing, regulatory processes continue towards evaluating lorcaserin as a potentially marketed weight-loss and weight-maintenance agent. Some of the challenges facing lorcaserin are similar to the difficulties encountered by all investigational weight-loss therapeutic agents, which include evolving paths towards approval. While important for clinicians to understand approval hurdles for all therapeutics, it is especially critical for researchers and developers to grasp the unique regulatory complexities of anti-obesity agents. This article profiles lorcaserin as an illustrative example of general drug development regulatory processes, and specifically details the unique challenge of weight-loss drug development.