The goal of this paper is to review the evidence related to the effect of plant-based dietary patterns on obesity and weight loss, including both observational and intervention trials. Literature from plant-based diets (PBDs) epidemiological and clinical trial research was used to inform this review. In addition, data on dietary quality, adherence, and acceptability were evaluated and are presented. Both clinical trials and observational research indicate an advantage to adoption of PBDs for preventing overweight and obesity and promoting weight loss. PBDs may also confer higher levels of diet quality than are observed with other therapeutic diet approaches, with similar levels of adherence and acceptability. Future studies should utilize health behavior theory to inform intervention development and delivery of PBDs studies and new technologies to bring interventions to scale for greater public health impact. Research examining PBDs and weight loss is also needed with more diverse populations, including older adults. Based on the available evidence, PBDs should be considered a viable option for the treatment and prevention of overweight and obesity.