The experimental implantable gastric stimulation device, also known as the “stomach pacemaker” has been shown to be an effective alternative to radical surgery such as the gastric bypass for helping people shed large amounts of weight.

The pacemaker — manufactured by Transneuronix — is a battery-powered generator about the size of a pocket watch. In clinical trials, it has helped hundreds of obese patients lose weight and keep it off.

Bill Martin, a 53-year-old electrician, lost 85 pounds in five years after having the pacemaker implanted.

“I noticed I was able to control my eating a lot better,” Martin said. “I was able to just stop and not overeat at all.”

During the implantation surgery, doctors use a minimally invasive procedure to place the generator under the skin in the abdomen and stitch its electrodes to the stomach wall. The outpatient surgery requires general anesthesia and takes less than an hour. Once installed, the device sends a mild burst of electrical current every three seconds.

Dr. Jay Prystowsky, a gastrointestinal surgeon at Northwestern Memorial Hospital in Chicago — one of eight sites currently participating in a clinical trial of the pacemaker — says researchers haven’t determined exactly how it works.

“For reasons that aren’t completely clear, the gastric pacemaker helps people to eat less, and therefore lose weight,” he said. “There’s no shock, no vibration, no sensation whatsoever, but the result is a reduced appetite. Patients say they feel full faster.”

The reduced appetite, according to one theory, could stem from the electrical current that is constantly stimulating the stomach muscle and disrupting production of a critical hunger hormone.

“People who lost weight with the stomach pacemaker had lower levels of a hormone that stimulates appetite,” said Dr. Louis Aronne, an obesity specialist at New York Presbyterian Hospital in New York. “As a result, they were not as hungry.”

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