For the first time in eight years, the Food and Drug Administration has approved a new weight loss device — the Maestro Rechargeable System.

The Maestro Rechargeable System is an implantable device that generates an electrical pulse to the vagus nerve, which tells the brain whether the stomach is full or empty, in order to electronically suppress hunger signals.

The product has been compared to a pacemaker, and is available to patients who have pre-existing conditions, such as Type 2 Diabetes, who are morbidly obese, or who haven’t had much success with other supervised weight loss programs in the past five years.

Though the FDA has approved four different weight loss drugs in the past three years, it’s been nearly a decade since it’s approved a weight loss device. In fact, the Maestro Rechargeable System is now only one of three FDA approved devices. The other two are gastric bands, silicone devices that restrict the amount of food patients can comfortably eat.

However, researchers aren’t entirely sure why stimulating the vagus nerve might make people feel less hungry.

“I suspect it blinds the brain of what’s going on in the gastrointestinal tract,” says Dr. Scott Shikora, consulting chief medical officer to EnteroMedics, which manufactures the device.

Though the FDA approved the device, the agency didn’t measure any of the other factors that might have contributed to patients’ weight loss, such what foods were being eaten or the portion sizes.

In a clinical trial published in the Journal of the American Medical Association, 233 Australian and American patients with a BMI of 35 or greater used the Maestro Rechargeable System for 18 months. The group had an average BMI of 41, which means that a person who is 5’8″ would weigh 270 pounds. They were considered about 97 pounds overweight on average. Some had the device turned on, while others had it implanted, but inactive.

After a year, the group with the device turned on had lost about 24% of their excess weight, or about 9% of their total body weight. The group with inactive devices lost 16% of their excess weight, or 6% of their total body weight. Researchers speculate that the control group lost weight as the result of a placebo effect, and because they were dieting and exercising.

Although the device did not help people lose 10% more excess weight than the control group, which was the study’s target, the FDA Advisory Committee on Gastroenterology-Urology Devices found that its benefits were still significant enough to approve it for patients meeting certain criteria.

Researchers not involved with the device warn that the results only show moderate weight loss, which shouldn’t be overstated.

“It is possible that this will be a component of treatment of obesity, but it’s too early to tell,” said Dr. Dario Englot, a neurosurgeon who’s studied vagus nerve stimulation for epilepsy. However, “Because obesity is such a problem, I think it’s a positive step to try new treatments as long as we know that they’re safe, and we know now that this is relatively safe.”