Dr. Sayeed Ikramuddin is no stranger to weight-loss surgery. He's done it at least 3,000 times.

But the University of Minnesota surgeon knows that some people, no matter how overweight, can't fathom the idea of having their internal organs snipped, tied or rearranged.

Now he's trying to find out if an implantable device can help them lose weight by interfering with their ability to feel hunger.

This summer, Ikramuddin plans to implant the device, made by a St. Paul company called EnteroMedics, in up to 30 volunteers as part of an international research study.

It's a new frontier in obesity research: focusing on the parts of the brain that control the urge to eat.

Obesity has become a huge issue not only for individuals who struggle to lose weight, but also with the increased health care costs from weight-related medical problems, such as diabetes. With 134 million Americans overweight or obese, some are betting the solution may lie in a new kind of technology that literally taps into the power of the mind.

More than 80 potential recruits showed up this month to hear about the experiment at the University of Minnesota, one of 15 sites testing the device (the Mayo Clinic is another). "The room was full each time," said Ikramuddin, who hosted three information sessions. "Everybody wants to lose weight. The issue is, how?"

In this case, a pacemaker-like device is inserted just beneath the skin near the rib cage. It sends electrical impulses to block the vagus nerve, which tells the brain when the stomach is empty. The idea, in effect, is to trick the brain in order to curb the appetite.

So far, attempts to use technology to tame hunger have been hit or miss. In 2005, Medtronic shelved one such device, which was designed to make people feel full by stimulating the stomach, after tests showed it didn't help them lose weight.

Yet last year, when scientists at the VA Medical Center in Minneapolis tested a nerve-stimulation device for depression, they discovered that many of the subjects unexpectedly lost weight, too. They called it a "serendipitous observation."

The EnteroMedics device, known as VBLOC, has shown some promise in a series of small studies. The latest, released June 19, tracked 12 obese patients who had the device for a year and found that they lost an average of 29 percent of their "excess weight."

Mayo Clinic researchers, who helped develop the device, found an average weight loss of 15 percent in six months, in a separate study. They concluded that the device "shows promise as a reversible and less extreme alternative to existing bariatric surgeries."

Now the company has set out to prove its worth in a larger study, with 300 participants, in hopes of winning approval from the Food and Drug Administration.

Turning down a nerve

Mark Knudson, who founded EnteroMedics, said he saw a "huge unmet need" when he came up with the idea for the weight-loss device.

An estimated 64 million Americans are obese, and the most effective treatment -- bypass surgery -- can be unpleasant and risky, with strict diets (liquids and purees for several weeks) and nasty side effects if patients eat the wrong things.

Knudson, who has made a career inventing medical devices, was looking for a kinder, gentler and more high-tech solution. With a device, "the anatomy is not permanently altered," he said. "It doesn't require them to undergo a permanent and onerous lifestyle change."

Scientists have long suspected that some people overeat because of a faulty connection in the brain. They don't get the message that they're full, so "they just don't know when to stop eating," said Knudson.

He and his colleagues focused on the vagus nerve, which sends messages between the digestive system and the brain.

Years ago, doctors discovered that cutting the vagus nerve -- once a common treatment for peptic ulcers -- could also cause weight loss.

Even today, they're not sure why, said Dr. Charles Billington, an obesity researcher at the University of Minnesota and VA Medical Center who is a consultant on the EnteroMedics study. That discovery has fueled interest by several companies in finding ways to manipulate the vagus nerve.

"We realized that you needed to turn that nerve off ... or at least turn it down," said Knudson. "That's what we did."

The device, which is connected to the nerve by wires, pulses on and off every five minutes while the patient is awake (it's turned off at night).

"It's like a stoplight for the nerve," said Knudson. "It prevents the signals from the stomach and the rest of your gastrointestinal tract from going up to the brain and telling the brain that you're hungry."

The result: "It allows patients to feel that feeling of fullness and push back from the table sooner," he said.

He estimates the overall cost will be comparable to bariatric surgery: about $35,000. But he admits there's no way of knowing how long the pounds will stay off.

'Learning how to eat again'

After 25 years of battling her weight, Cindy Leehy, a saleswoman in Richmond, Va., had the device implanted in April.

Since then, she has lost 18 pounds toward her goal of 80 pounds. Technically, she doesn't know whether the device is working: as part of the study, it's turned off in about a third of the patients for the first year.

But she believes it has helped change her ways. "It wasn't a quick and easy fix," said Leehy, 46. "It was learning how to eat again with the help of the implant." Along with the device, she's received coaching on nutrition and weight-loss tips.

"The whole point is, they're trying to teach you to stop eating when you get full," she said. She said she's barely aware of the device, except for occasional "waves of sensation" in her esophagus and the battery pack she wears on a belt. Meanwhile, she's still losing weight. "That to me says I picked the right program," she said.

The researchers, though, say there's a lot to learn before it's ready for prime time.

They still don't know what kind of long-term effects it might have on the vagus nerve, said Ikramuddin, the surgeon. He also wonders how willing patients will be to change their old habits. Even with weight-loss surgery, he notes, "if you don't exercise and eat right ... it's all coming back."

Billington said everyone is searching for the same thing in obesity treatment: something that has a big impact, few side effects and a long-lasting effect.

"So far, as I think everyone knows, we haven't had a lot of luck finding those things," he said. "I don't think there is [one] answer. I think we're going to need a lot of answers."

Maura Lerner • 612-673-7384