updated 1/22/2008 7:12:15 PM ET 2008-01-23T00:12:15

Within a few years, Americans may have a new tool to fight back against obesity: electricity.

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Not from the power grid, but from implanted pacemaker-like devices that influence a key nerve linked to food-related functions, including feelings of hunger and fullness.

The quest for obesity-fighting drugs and devices is a tricky area where companies have stumbled before, and hacking into the nervous system can prove challenging. But it's also a potentially huge market given the prevalence of obesity and the scarcity of useful, low-impact treatments.

Around one-third of Americans over age 20 are overweight enough to be considered obese, and the excess pounds are linked to other maladies, such as diabetes and heart disease.

Drugs have yet to play a significant obesity-fighting role, while invasive surgical procedures, such as gastric bypass, are a serious option for seriously endangered patients. Some medical technology companies have been chasing the implanted electrical-device angle to help fill the void.

Companies checking out the market include Medtronic Inc., St. Jude Medical Inc. and health-care giant Johnson & Johnson, which just signaled interest by buying the rights to patents for a nerve-stimulation technology from Cyberonics Inc.

A St. Paul, Minn.-based company called EnteroMedics Inc. is testing an implantable device called Maestro that periodically blocks transmission on the digestion-controlling vagus nerve. Limited study data suggests it may trigger significant weight loss. A bigger, yearlong randomized study that's enrolling over the next six months could put the company on track for U.S. approval in the middle of 2010, if things go well.

If approved, the technology could give weight-loss surgeons a significant new tool.

Safer than bypass
"A technology like this is dramatically safer than gastric bypass," said Scott Shikora, chief of bariatric surgery at the Tufts-New England Medical Center in Massachusetts, which will take part in the trial for Maestro. Shikora is a paid medical consultant for EnteroMedics.

Bypasses dramatically shrink the space for food and can lead to significant weight loss. But because of the severity and permanence of the procedures, and surgical risks, it's generally reserved for people more threatened by obesity itself, Shikora said.

The Maestro device likely wouldn't produce the same weight loss as gastric bypass, but it could fill a niche somewhere between the limits of drug therapy and the severity of bypass operations, according to Mark Knudson, EnteroMedics's president and chief executive, and also a co-founder.

By blocking the vagus nerve signals, Maestro may affect a host of systems to help patients shed weight, as suggested by limited studies thus far outside the United States. Among patents studied, EnteroMedics announced on Jan. 8 that nine device patients followed out to nine months had lost 29.5 percent of their excess weight.

The goal of the big trial for the device, called "Empower," is to reduce excess weight by 25 percent, Knudson said, although he expects a steeper cut. Obesity is diagnosed when a person's body mass index, a mathematical formula measuring weight and height, equals or tops 30. Knudson sees a potential pool of 13 million device candidates in the U.S., made up of people who are significantly over that threshold and may have obesity-related conditions.

Gastric bands that limit food intake are another surgical option for weight loss, are considerably cheaper initially, and are also less invasive than bypass surgery. But Shikora, who had yet to implant a Maestro device as of a recent interview, said he also believes devices could prove a bit safer overall than gastric bands, which can have some complications and require follow-up adjustments that add to their expense.

The version of EnteroMedics's technology being tested requires patients to wear a belt that transmits power and programming to the implanted component, which means patients in the trial will have to dutifully wear the belt to ensure success. The company is working on a fully implantable version, too.

Copyright 2008 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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