This single-center, randomized, single-blind, sham-controlled pilot study aims to evaluate the adjunctive effect of transcutaneous auricular vagus nerve stimulation (taVNS) in overweight/obese patients who show a poor weight loss response to lifestyle intervention. Participants who achieve no more than 5% weight loss after 12 weeks of lifestyle intervention will be randomized to receive either taVNS plus lifestyle intervention or sham stimulation plus lifestyle intervention for an additional 12 weeks. The primary objective is to compare the percent change in body weight from baseline between the two groups after 12 weeks of intervention. Secondary objectives include evaluation of changes in body composition and fat distribution, autonomic function, liver-related parameters, and glycemic and lipid-related metabolic parameters.
Completed 12 weeks of lifestyle intervention treatment with ≤5% weight loss during the treatment period;
Completed 12 weeks of lifestyle intervention, with less than 1 month since completion, and achieved ≤5% weight loss during the intervention period;
Current body mass index (BMI) ≥28 kg/m², or BMI ≥24 kg/m² with at least one weight-related comorbidity (e.g., hypertension or fatty liver disease);
Willingness to provide written informed consent.
Presence of diseases that may substantially affect body weight homeostasis, including Cushing's syndrome, uncontrolled thyroid disease (thyroid-stimulating hormone >6.0 mIU/L or <0.4 mIU/L), malignancy, or similar conditions;
Use within the past 3 months of medications that may significantly affect body weight, including glucocorticoids and antipsychotic agents;
Skin infection or damage involving the auricular area;
Women planning pregnancy in the near future;
Parallel
transcutaneous auricular vagus nerve stimulation
DeviceParticipants will receive active transcutaneous auricular vagus nerve stimulation in addition to lifestyle Intervention for 12 weeks. Active stimulation will be delivered to the left cymba conchae using an intermittent waveform (15 seconds on, 5 seconds off) at 20 Hz with a pulse width of 0.2 ms. Stimulation intensity will be titrated from 0 mA to a level that produces mild tingling without obvious discomfort, usually 1.0-2.5 mA. Stimulation will be administered twice daily for 30 minutes per session, 5 days per week, for 12 weeks.
Sham
DeviceParticipants will receive sham stimulation in addition to lifestyle Intervention for 12 weeks. Sham stimulation will be applied to the left tail of the helix using the same waveform parameters, stimulation intensity titration, and treatment schedule as the active group, namely twice daily for 30 minutes per session, 5 days per week, for 12 weeks.
Percent Change in Body Weight From Baseline
Percent change in body weight from baseline to week 12 will be compared between the taVNS plus lifestyle intervention group and the sham stimulation plus lifestyle intervention group to evaluate the adjunctive effect of taVNS on weight reduction.
Change in Waist Circumference
Change in waist circumference from baseline to Week 4, Week 8, and Week 12 will be assessed using standardized Change in waist circumference from baseline to Week 4, Week 8, and Week 12 will be assessed using standardized anthropometric measurement. Change in waist circumference from baseline to Week 4, Week 8, and Week 12 will be assessed using standardized anthropometric measurement.
Change in Body Composition and Fat Distribution
Changes in body composition and fat distribution will be assessed by body fat percentage using anthropometric measurements and body composition analysis
Change in Visceral Fat Area
Change in visceral fat area from baseline to Week 4, Week 8, and Week 12 will be assessed using body composition analysis.
Change in blood glucose
Change in fasting blood glucose from baseline to Week 12 will be assessed using laboratory testing.
Change in Brain Biotype
Changes in brain biotype after 12 weeks of intervention will be explored using brain MRI-based analyses. Brain biotype will be assessed at baseline and Week 12 using brain MRI-based analyses. Brain biotype will be defined as an MRI-derived classification based on pre-specified brain imaging features, such as resting-state functional connectivity patterns. Participants will be assigned to a brain biotype category according to the pre-specified MRI analysis algorithm.
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