Various systems and methods for predicting metabolic and bariatric surgery outcomes are provided. The systems and methods can also provide predictions for non-surgical metabolic and bariatric treatments. In general, a user can receive predictive outcomes of multiple bariatric procedures that could be performed on a patient. In one embodiment, a user can electronically access a metabolic and bariatric surgery outcome prediction system, e.g., using one or more web pages. The system can provide predictive outcomes of one or more different bariatric surgeries for the patient based on data gathered from the user and on historical data regarding outcomes of the different bariatric surgeries. The system can additionally provide predictive outcomes for not having any treatment and/or a comparison of the predictive outcomes of the one or more different bariatric surgeries to the predictive outcomes for not having any treatment.