This invention disclosed methods and devices for effecting a gastric restriction system, further, related to sensor trigger. In one exemplary embodiment, a restriction system for forming a restriction in a patient is provided and can include an implantable restriction device and at least one implantable sensor that is in communication with the restriction device. In general, the implantable restriction device can be adjustable and can be configured to form a restriction in a patient. The implantable sensor(s) can be defaulted to a dormant power usage mode and can have a triggering mechanism that is configured to place the sensor(s) in a use configuration upon the occurrence of a triggering event.