LONDON — Patrick Hetzner tried diets and exercise, just about everything short of stomach stapling to lose weight. Nothing worked. Five months ago he tried something new: a stomach pacemaker that curbed his appetite.

Since having it implanted, Hetzner, a 20-year-old Munich mailman, has knocked off more than 22 pounds from his earlier weight of 229.

Hetzner got the device as part of a clinical trial. Since being approved by Britain last month, the device is available for sale across the European Union. It works a bit like a cardiac pacemaker, and consists of a stimulator and a sensor surgically implanted onto the stomach.

The stimulator sends out electrical pulses meant to trick the stomach and brain into thinking the body is full. Hetzner said the pulses kick in a few minutes after he starts eating or drinking. He said they make him feel full after finishing about half the amount of food he would normally eat.

“It feels like a little pressure on my stomach or a tickle, but it’s not a bad feeling,” he said in a telephone interview.

“It’s been like a little guide to help me change my life,” he said.

So far, about 65 patients in two studies have received the device from U.S. pacemaker manufacturer Intrapace. Only about half of those have had the pacemaker for at least a year, and most lost about 20 percent of their weight and kept it off.

Other stomach pacemakers are on the market but most are used to relieve symptoms like nausea and vomiting, not to fight obesity.

Appetite is partly controlled by signals sent from nerves around the stomach to the brain; the stomach pacemaker taps into that communication system, sending a message to the brain that the body is full after a relatively small amount of food is consumed.

“If you can stimulate the nerves going from the stomach to the brain, that should indeed have an effect in reducing food intake,” said Stephen Bloom, an obesity expert at Imperial College in London, who is not connected to Intrapace or the clinical trials.

Doctors familiar with the pacemaker say there will always be ways for patients to eat and work around the system. “We could make the (stomach pacemaker) work so people feel like they’re going to throw up, but we don’t want that,” said Thomas Horbach, chief of surgery at Stadtkrankenhaus Schwabach, near Munich, who led one of the trials.

“If you take away all the responsibilities from the patient, they will not change on their own.”