Effects of Transcutaneous Auricular Vagus Nerve Stimulation on Appetite

Effect of Transcutaneous Auricular Vagus Nerve Stimulation on Food Intake: A Randomized, Double-Blind, Sham-Controlled Crossover Study

This study tests a new way to help control appetite. Researchers will use a wearable device on the ear. This device sends gentle electrical pulses to a nerve. This is called vagus nerve stimulation.

The main goals of this study are:

• To see if this device helps people eat less.
• To check if it lowers feelings of hunger.
• To measure how it changes responses to food cues.

Healthy adult women will join this study. Each person will have two study visits. At one visit, the device will be turned on. At the other visit, the device will be off. This is a fake or "sham" treatment.

During each visit, researchers will:

• Give a standard meal for 30 minutes.
• Measure how much food each person eats.
• Ask questions about hunger and fullness.
• Use computer tasks to check food cravings.

This study may find a safe, medicine-free way to manage eating habits.

Study Overview

• Status: Completed
• Conditions: Obesity; Food Intake; Appetite Regulation; Eating Behaviour
• Intervention / Treatment: Device: Transcutaneous Auricular Vagus Nerve Stimulation (taVNS); Device: Sham Stimulation

Detailed Description

Background and Rationale Despite substantial advances in pharmacological treatments for obesity, a considerable proportion of individuals remain non-responsive or intolerant to current medications. This highlights the urgent need for novel, sustainable, and non-pharmacological interventions. Transcutaneous auricular vagus nerve stimulation (taVNS) is an emerging non-invasive electroceutical approach. It targets the vagal afferent pathway to modulate the brain-gut axis, potentially influencing appetite regulation through neurophysiological circuits related to satiety, reward, and interoceptive processing.

Study Protocol and Procedures This study employs a double-blind, sham-controlled, crossover design. Participants will complete two separate experimental visits, separated by a washout period of at least 24 hours to prevent carryover effects. The sequence of the active and sham conditions will be strictly counterbalanced across participants.

During each experimental session, participants will first undergo baseline assessments. Following baseline, the investigational wearable device will be applied to the participant's ear. For the active condition, stimulation will be targeted at the left cymba conchae. The device is programmed with specific technical parameters, including a frequency of 20 Hz, a 50% duty cycle, and an intensity of 1 mA. For the sham condition, the setup will be identical in appearance but will lack the therapeutic electrical dosage to maintain double-blinding for both the investigator and the participant.

The designated stimulation (active or sham) will be delivered continuously for exactly 30 minutes. Concurrently with the stimulation, participants will be presented with a standardized, ad libitum buffet-style test meal. Immediately following the 30-minute eating and stimulation session, participants will engage in a series of computerized cognitive-behavioral tasks and state-assessment surveys designed to capture neurocognitive responses to food cues and interoceptive awareness.

• Study Type: Interventional
• Enrollment (Actual): 60
• Phase: Not Applicable

Contacts and Locations

Study Locations

• South Korea
  • Seoul, South Korea
    • Seoul National University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Female participants aged between 20 and 50 years
• Body Mass Index (BMI) of 20 or higher
• Individuals who are capable of understanding the study procedures and providing voluntary informed consent

Exclusion Criteria:

• Presence of implanted metallic or electronic medical devices (e.g., cardiac pacemaker, implantable cardioverter defibrillator (ICD), cardiac stent, deep brain stimulator, or cochlear implant), except for dental implants and artificial joints
• History of diagnosed psychiatric disorders or current use of psychiatric medications
• Moderate to severe depression symptoms, defined as a Patient Health Questionnaire-9 (PHQ-9) score of 10 or higher
• Use of medications or medical interventions that may induce weight changes within the past 3 months
• Active inflammatory or infectious lesions on the ear (e.g., otitis externa, auricular dermatitis, or active skin infection)
• Specific dietary habits or restrictions, such as being a vegan or vegetarian
• Known food allergies
• Currently pregnant or breastfeeding
• History of diagnosed diabetes or other endocrine metabolic diseases
• Any other medical condition, illness, or history that, in the investigator's judgment, would make it difficult for the participant to complete the study or complicate the interpretation of study results

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Active then Sham; Participants receive a single 30-minute session of active taVNS in the first period. Following a washout period of at least 24 hours to prevent carry-over effects, they return for a second visit to receive a single 30-minute session of sham stimulation.	Device: Transcutaneous Auricular Vagus Nerve Stimulation (taVNS); A single 30-minute session of active taVNS (20 Hz, 1 mA, 50% duty cycle) will be administered to the left cymba conchae. As this is a crossover study, each participant receives this intervention once during their assigned active period.; Device: Sham Stimulation; A single 30-minute session of sham stimulation will be administered at the same location (left cymba conchae). The device is applied for 30 minutes with the same visual and tactile setup, but no effective electrical stimulation is delivered. This is performed once during the participant's assigned sham period.
Experimental: Sham then Active; Participants receive a single 30-minute session of sham stimulation in the first period. Following a washout period of at least 24 hours, they return for a second visit to receive a single 30-minute session of active taVNS.	Device: Transcutaneous Auricular Vagus Nerve Stimulation (taVNS); A single 30-minute session of active taVNS (20 Hz, 1 mA, 50% duty cycle) will be administered to the left cymba conchae. As this is a crossover study, each participant receives this intervention once during their assigned active period.; Device: Sham Stimulation; A single 30-minute session of sham stimulation will be administered at the same location (left cymba conchae). The device is applied for 30 minutes with the same visual and tactile setup, but no effective electrical stimulation is delivered. This is performed once during the participant's assigned sham period.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Difference in Food Intake	The amount of food consumed during an ad libitum buffet meal (standardized Gimbap). It is calculated as the difference in the weight of food (grams) consumed between the active taVNS session and the sham stimulation session.	During the 30-minute ad libitum meal session in each experimental visit

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Attentional Bias Toward Food Stimuli	Attentional bias measured via a Dot-probe task. It is calculated based on the difference in reaction times (ms) between dots replacing food images versus neutral images.	Immediately after the 30-minute stimulation/meal session.
custom-developed Interoceptive State Appetite Scale (VAS-100)	Subjective states of hunger, fullness, and desire to eat are assessed using the 15-item Interoceptive State Appetite Scale (VAS-100). Each of the 15 items is evaluated on a 0 to 100 scale, where higher scores indicate greater intensity of the felt state. All 15 items share the identical unit of measure (VAS score, 0-100) and will not be aggregated into a composite score. Instead, the individual score for each of the 15 items will be reported separately to evaluate their independent changes.	Baseline (pre-stimulation) and immediately after the 30-minute stimulation/meal session.
Eating-Related Interoceptive Awareness	This measure assesses the participant's ability to perceive and respond to internal bodily signals related to hunger, satiety, and food intake control using a 7-item questionnaire. Six items are rated on a 5-point Likert scale (1-5), and one item is rated on a 6-point Likert scale (1-6). The individual score for each of the 7 items will be analyzed and reported separately.	Immediately after the ad libitum buffet meal and the final VAS-100 appetite assessment in each experimental session.
Inhibitory Control Toward Food Cues: False Alarm Rate	Performance on a Go/No-Go task to measure response inhibition toward food-related stimuli. The specific indicator is the False Alarm Rate, defined as the proportion of incorrect responses during No-Go trials. To evaluate the intervention effect, the difference in False Alarm Rates between the active stimulation session and the sham session will be calculated and analyzed using a paired t-test.	Immediately after dot probe task
Inhibitory Control Toward Food Cues: d-prime	Performance on a Go/No-Go task to measure signal detection sensitivity and response inhibition toward food-related stimuli. The specific indicator is the $d'$ (d-prime) index, calculated based on the standardized hit rates and false alarm rates. To evaluate the intervention effect, the difference in $d'$ values between the active stimulation session and the sham session will be calculated and analyzed using a paired t-test.	Immediately after the Dot-probe task

Collaborators and Investigators

• Sponsor: Seoul National University Hospital
• Investigators: Principal Investigator: Hyung Jin Choi, MD, PhD, Seoul National University College of Medicine

Study record dates

Study Major Dates

• Study Start (Actual): January 12, 2026
• Primary Completion (Actual): February 12, 2026
• Study Completion (Actual): February 12, 2026

Study Registration Dates

• First Submitted: February 23, 2026
• First Submitted That Met QC Criteria: February 23, 2026
• First Posted (Actual): March 2, 2026

Study Record Updates

• Last Update Posted (Actual): March 4, 2026
• Last Update Submitted That Met QC Criteria: March 2, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Nutrition Disorders; Overnutrition; Body Weight; Overweight; Pathological Conditions, Signs and Symptoms; Behavior; Nutritional and Metabolic Diseases; Signs and Symptoms; Behavior, Animal; Obesity; Feeding Behavior
• Other Study ID Numbers: 2506-159-1654

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: IPD will not be shared to protect the privacy of the participants and to comply with the institutional review board (IRB) approval, which does not include a provision for public data sharing.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No