Investigating the Microbiota-Gut-Brain Axis Mechanisms of Transcutaneous Auricular Vagus Nerve Stimulation in Patients with Obesity: A Study Protocol for a Randomized Controlled Trial

Oct 27, 2025Diabetes, metabolic syndrome and obesity : targets and therapy

How Ear Nerve Stimulation May Affect the Gut-Brain Connection in People with Obesity

AI simplified

Gut-Brain Axis on OpenScience ↗PubMed ↗DOI ↗OA ↗

Abstract

A total of 74 patients with obesity will be enrolled in a randomized controlled trial to evaluate the effects of transcutaneous auricular vagus nerve stimulation (taVNS) on body weight.

The primary outcome is the percentage change in body weight from baseline to Week 12.
Secondary outcomes include changes in body mass index (BMI), waist circumference, hip circumference, body fat percentage, and visceral fat area.
Clinical evaluations will assess quality of life, perceived stress, depression, eating behavior, physical activity, and fatigue.
The study will measure serum brain-gut peptides and gut microbiota composition to explore the microbiota-gut-brain axis.
Functional magnetic resonance imaging (fMRI) will be used to evaluate changes in neural activity.

AI simplified

BACKGROUND: Obesity is a common metabolic disorder affecting nearly one-third of the global population. Emerging evidence indicates that the microbiota-gut-brain axis plays a key role in the pathogenesis of obesity. Transcutaneous auricular vagus nerve stimulation (taVNS), a non-invasive neuromodulation technique, may modulate brain function and gut microbiota via vagal pathways. This study aims to evaluate the short-term efficacy of taVNS in reducing body weight in patients with obesity and to explore its underlying mechanisms by assessing changes in neural activity and gut microbial composition.

METHODS: This single-center, randomized controlled trial will enroll 74 patients with obesity, who will be randomized in a 1:1 ratio to receive either taVNS (electrical stimulation delivered to the left cymba conchae) or sham taVNS (stimulation at the tail of the helix). The primary outcome will be the percentage change in body weight from baseline to Week 12. Secondary outcomes will include anthropometric measures such as changes in body mass index (BMI), waist circumference, hip circumference, body fat percentage, and visceral fat area. Clinical evaluations will be conducted using validated instruments, including the Impact of Weight on Quality of Life-Lite (IWQOL-Lite), Perceived Stress Scale (PSS), Hamilton Depression Rating Scale (HAMD), Dutch Eating Behavior Questionnaire (DEBQ), International Physical Activity Questionnaire (IPAQ), and the Fatigue Scale-14 (FS-14). To investigate modulation of the microbiota-gut-brain (MGB) axis, assessments will include serum brain-gut peptides, gut microbiota composition, and functional magnetic resonance imaging (fMRI). Adverse events will also be systematically monitored throughout the study period.

DISCUSSION: This study will preliminarily validate the clinical efficacy of taVNS for obesity. And by integrating measures such as gut peptides, microbiota profiling, and brain imaging, it seeks to link therapeutic effects with microbiota-gut-brain axis modulation. The findings may support taVNS as a safe, non-pharmacological approach for obesity management and inform future neuromodulation-based strategies.

TRIAL REGISTRATION NUMBER: ITMCTR2024000518. http://itmctr.ccebtcm.org.cn/zh-CN/Home/ProjectView?pid=d4ae9741-2788-433a-9242-a5fe78929bce.

Key numbers

74 subjects

Sample Size

Total participants enrolled in the trial

Weight Change Expectation

Average weight loss anticipated after 12 weeks of intervention

20%

Dropout Rate

Estimated percentage of participants expected to drop out during the study

Full Text

We can’t show the full text here under this license. Use the link below to read it at the source.

View full text (PDF) ↗

Investigating the Microbiota-Gut-Brain Axis Mechanisms of Transcutaneous Auricular Vagus Nerve Stimulation in Patients with Obesity: A Study Protocol for a Randomized Controlled Trial

Abstract

Key numbers

Full Text

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the gut-brain axis brief

Abstract

Key numbers

Full Text

Related papers

You found one interesting study. We’ll send the next 7.

what lands in your inbox each week:

Recent issues from the gut-brain axis brief