The present invention is directed to a method of regulating gastrointestinal action in a subject using a stimulatory electrode and a sensor to provide retrograde feedback control of electrical stimulation to the GI tract. The invention is further directed to a method for reducing weight in a subject, again using a stimulatory electrode and a sensor to provide retrograde feedback control of electrical stimulation to the stomach. The invention is further directed to a method of providing electrical field stimulation to a gastrointestinal organ, as well as a method of providing an electrical potential gradient in a gastrointestinal organ. Further provided is a method of stimulating the vagus nerve of a subject. Additionally provided is a method of placing a device in the gastrointestinal tract or wall of a subject from the exterior of the subject, using a needle to insert the device.