Freezing the 'hunger nerve' could help with weight loss

Weight loss can sometimes seem impossible because even after hard-won success, the pounds can creep back.

“Ninety-five percent of people who embark on a diet on their own will fail or gain their weight back at the six- or 12-month mark,” Dr. David Prologo, an interventional radiologist at Emory University School of Medicine in Atlanta, said in a news release video. “The reason for this is the body’s backlash to the calorie restriction."

Prologo recently conducted a trial that looked deeper into the issue, targeting the "hunger nerve" and its possible connection to one's ability to lose weight and keep it off.

The “hunger nerve” -- also known as the posterior vagal trunk -- is a branch of the larger vagus nerve that works on the heart, lungs and GI system. When your stomach is empty, the nerve signals your brain that you're hungry.

For a small study based at Emory University School of Medicine, Porlogo and researchers tried a minor surgical procedure on the study's participants where a probe was inserted into the patient’s back, freezing the nerve for two minutes, with the guidance of live images from a CT scan. By freezing the nerve, the hunger signal was shut down.

The experiment was meant solely to test the safety of the procedure, and the team ran the study on only 10 people. All were overweight, between the ages of 27 to 66 and had body mass indexes (BMIs) ranging from 30 and 37 (those stretch from "moderately" to "severely" obese). Eight of the 10 participants were women.

At the end of the procedure, the probe was removed and a small bandage was applied to the skin, with patients going home the same day.

The researchers saw the patients again seven, 45 and 90 days after the procedure. Because it was a phase 1 trial, primarily looking for negative side effects, the technical success rate was 100 percent, there were no procedure-related complications and no adverse events on which to follow up.

Though they weren't really looking at weight effects at this stage, patients said they had a decreased appetite at each clinic appointment, and there was an average weight loss of 3.6 percent. Additionally, all of the participants' BMI numbers came down about 13.9 percent. There was no mention of how long any effects on the nerve might last.

“I had struggled with weight since my 6-year-old was born ... and I’m constantly rebounding [with various weight-loss programs],” Prologo’s first patient, Melissa, said in the news release video.

After the procedure, she said, “I’m literally never hungry ... I’m not eating because I’m bored. It’s gradually coming off, so now I know it’s not going to come right back on like all the previous diets that I’ve tried."

Ten other patients also had the procedure but the researchers have yet to analyze the results. The next goal for the research team is to enroll people in a phase 2 study so they can have a control group for comparing possible results.

This study was presented at the Society for Interventional Radiology Conference this week in Los Angeles, and has not been published in a peer-reviewed medical journal.

It is far from proven that freezing the nerve will result in permanent weight loss but if it does, it could have a profound effect on the lives of those who have struggled to maintain a healthy weight.

Najibah Rehman, MD, with a Master of Public Health, is a third-year preventive medicine resident at the University of Michigan in Ann Arbor, working in the ABC News Medical Unit.