Methods and devices are provided for predicting performance of a restriction system for a patient. In general, the methods and devices can allow detection and prediction of a trajectory of a particular patient attribute, such as weight loss. Using previously gathered data values, data values defining a future outcome can be predicted and compared with a desired future outcome. If the future outcome deviates from the desired future outcome, one or more corrective actions can be suggested to a patient and/or a health care provider to help align the patient's treatment plan with the desired future outcome rather than the currently predicted future outcome.