An implant intended as a less drastic alternative to stomach stapling or stomach bypass surgery for the morbidly obese is now being sold in Europe. The device senses when a person is eating and generates a premature sensation of fullness by stimulating nerves that curl around the stomach.

The implant, developed by Intrapace, a company based in Mountain View California, is available in Germany, Spain, and the U.K.; the first implantations are scheduled to be carried out later this week. In trials involving 65 patients, the company says, the device led to an average weight loss of 22 percent after one year, with some patients losing as much as 38 percent of their body weight. These results have not yet been published.

The implant, called Abiliti, is also equipped with an accelerometer that shows a physician how much exercise the patient is getting. Data from the device can be uploaded to a computer wirelessly.

Abiliti is about the size of a pacemaker and is designed to be implanted within the abdominal cavity but outside the stomach through minimally invasive laparoscopic surgery. Two leads connect it to the stomach—one for sensing and the other for stimulating. A sensor is passed through the stomach wall; this detects when food enters. A stimulating electrode that’s been attached to stretch receptor nerves outside the stomach then sends sensations of fullness to the brain via the vagus nerve.

By detecting when food starts to enter the stomach, the implant is able to stimulate nerves prematurely and simulate sensations of being full before the stomach actually starts to fill, says Chuck Brynelsen, president and CEO of Intrapace.

Gastric neurostimulation has been proposed previously as a way of tackling obesity, but the success of such devices so far has been poor. A similar device developed by Transneuronix, a company in New Jersey, also used vagus-nerve stimulation. But after the company was bought by medical device giant Medtronic, trials with hundreds of patients showed no clear benefit, and the technology appears to have been scrapped.

Devices that stimulate the vagus nerve continuously can lead to habituation, in which the nerve adapts to the stimulus and essentially learns to ignore it.

“What’s unique about the Abiliti device, and what attracted me to it, is that it’s got the capacity for intelligent sensing,” says Abeezar Sarela a bariatric surgeon at the University of Leeds School of Medicine, in the U.K., who plans to start offering the device to his patients.

At a cost of around $21,000 for the device and surgery, Abiliti is slightly more expensive than a stomach bypass and nearly twice the price of a gastric band, says Sarela. However, it should have none of the side effects, such as nausea or vomiting can be caused by structurally altering the stomach, he says.

The only notable new side effect is a slight risk of infection due to the incision in the stomach, says Sarela. But even so, while Abiliti will be particularly suited to some patients, Sarela doesn’t see it replacing stomach stapling or bypasses for the vast majority of cases, at least not for the foreseeable future. “These will remain the workhorses of bariatric surgery,” he says.