First noticed in the 1940s
The vagus nerve's pivotal role in weight gain would appear to make it a prime target of obesity therapy. But this potential was discovered almost by accident in the 1940s, when surgeons treating intractable ulcers tried vagotomy to help reduce stomach acidity. The method worked, and soon became widely used (drug therapy eventually superseded it). But the operation had an unexpected side effect: It made obese patients lose weight.
Early vagotomy surgeries cut the entire vagus nerve as well as some stomach muscles. This drastic method caused undigested food to be dumped into the intestines, leading to a range of unpleasant side effects, such as diarrhea, vomiting, flushing and dizziness.
The modern form of the procedure is much more refined: It cuts only the parts of the vagus that control hunger and weight gain, leaving the stomach muscles and the rest of the nerve intact. As a result, the side effects of vagotomy are now much milder and tend to disappear after a few months, Lustig says.
Launched in 2005, the trial Lustig is involved in is taking place at UC San Francisco and the University of Rochester. About 80% of the 30 subjects in the trial lost an average of about 30% of their excess body weight in the first six months, Lustig says. The trial is sponsored by EndoVx, a Napa-based company that is developing a device to simplify the vagotomy procedure.
One of Lustig's patients, 57-year-old Garth Michaels of Walnut Creek, says he lost about 40 pounds within months of surgery. He got rid of 60 pounds more over the next year after starting a regular exercise program, and is down to a manageable 220 pounds.
"It's harder for extra weight to come on to me, and it's easier for it to fall off than it used to be," he says. In fact, he adds, he feels that his whole attitude toward food has changed for the better after his vagotomy. "I eat less food, eat it more slowly and enjoy it more."
Once the vagus nerve is cut, it can't be restored -- a potential drawback, because the reduced appetite and slowed digestion may no longer be required or even desirable once a patient attains a healthy body weight. And so some researchers are testing whether it's possible to achieve the weight loss effects of vagotomy while keeping the vagus nerve intact.
