In a new pilot study, doctors have shown that freezing the nerve that carries hunger signals to the brain may be able to lower a person’s appetite and help them lose weight.
Dieting is difficult, and most people who try it don’t sustain it for long. In an alternative approach to weight loss, Dr. David Prologo, an interventional radiologist from Emory University School of Medicine, and his colleagues froze a nerve called the posterior vagal trunk in 10 people who were significantly overweight. Their research was presented at Society of Interventional Radiology’s 2018 Annual Scientific Meeting.
The men and women in the study were categorized as having obesity (a body mass index (BMI) between 30 and 37) but did not meet the threshold for other interventions like gastric bypass surgery. In the study, doctors sedated them and inserted a needle into their backs; using CT guidance, they directed the needle to the posterior vagal trunk. The needle was filled with a gas that froze the needle and the surrounding nerve — a process that degenerates the part of the nerve connected to the brain and stops the signaling between the two. The entire procedure takes about 30 minutes and is painless, Prologo says. The same type of treatment has been used on different nerves to treat chronic pain.
Everyone in the initial trial reported a lowered appetite and some weight loss. 53% of people reported “very much less appetite,” 30% reported “much less appetite” and 17% of people reported “somewhat less appetite.” By eating less, the people were able to continue to lose weight. Overall, people lost an average of 3.6% of their initial body weight and had a nearly 14% decrease in excess BMI. There were no adverse side effects reported.
Prologo says he sees the procedure as being useful for people who are significantly overweight—with mild or moderate obesity—but who are tired of repeatedly failing at diets and who struggle with calorie restriction. “One subject characterized this procedure as ‘Antabuse for overeaters,’ which I thought captured it well,” says Prologo, referring to the drug for alcoholism that gives people an unpleasant reaction when they drink alcohol. “It is designed to make calorie restriction easier for people.”
The procedure isn’t permanent. The nerve will regrow at about one millimeter per day and will fully grow back after eight to 12 months. Prologo says there isn’t a risk that people’s hunger signals would not recover. “We know the nerve is going to regenerate,” he says. “We are able to do this because the body [also] has other backup systems” for cueing hunger.
This initial trial is considered a pilot study and was meant to only assess safety and feasibility. Prologo says a much larger trial with more people is needed to better understand if the procedure works in a lasting way.