A Phase 2 interventional study of Tirzepatide and Placebo in Obesity, sponsored by University Medical Centre Ljubljana. Completed at 1 site in Slovenia. Open to female participants aged 20 Years to 50 Years. Per ClinicalTrials.gov, last updated 2026-07-07.
Sponsored by University Medical Centre Ljubljana · Phase 2, Interventional, and Treatment
This study is testing whether a new anti-obesity medicine called tirzepatide can increase the activity of special fat cells in the body that help burn energy. These fat cells are known as brown and beige fat. The study includes women with obesity and will last 24 weeks.
Participants will receive either tirzepatide or a placebo (a look-alike injection with no active drug). Researchers will measure the amount and activity of brown fat using medical imaging (PET/CT, MRI, and thermal camera), and examine fat tissue samples to look for changes in gene activity and structure that show beige fat activation.
The study will also evaluate how these fat changes affect body weight, energy use, hormone levels, blood sugar, and other health markers. The goal is to learn whether tirzepatide helps improve metabolism by increasing energy-burning fat in addition to reducing appetite.
6,296 studies on the registry are indexed under Obesity; 1,692 are open to participants now.
This study's enrollment of 34 is below the median of 78 across 4,878 interventional studies indexed under Obesity.
Browse Obesity studies →University Medical Centre Ljubljana is the lead sponsor of 284 studies on the registry; 71 are open to participants now.
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Exclusion Criteria:
Drug: Tirzepatide
Drug: Placebo
Tirzepatide is a dual glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist. It will be administered via subcutaneous injection once weekly in a dose-titration scheme: starting at 2.5 mg, and increased every 4 weeks by 2.5 mg up to a maximum of 15 mg, based on tolerability. The medication will be supplied in prefilled pens identical in appearance to placebo pens.
Placebo will be administered via subcutaneous injection once weekly using pens that are visually indistinguishable from those used for tirzepatide. Dose escalation will follow the same schedule (2.5 mg-equivalent increments every 4 weeks) to preserve blinding integrity.
Change in Brown Adipose Tissue Activity and Volume
Assessed using 18F-FDG-PET/CT, magnetic resonance imaging (MRI), and infrared thermography. Outcome measured as change in mean standardized uptake value, supraclavicular skin temperature, and BAT volume in predefined anatomical regions (supraclavicular and cervical areas) between baseline and after 24 weeks of treatment.
Time frame: Baseline to Week 24
Change in Molecular Markers of Browning in Subcutaneous White Adipose Tissue
Measured as changes in the expression levels of uncoupling protein 1 (UCP1) and other browning-associated genes (via RT-PCR and RNA sequencing) in subcutaneous white adipose tissue (WAT) biopsies. Additionally, assessed through histomorphometric analysis of adipocyte phenotype, including the proportion of multilocular (plurivacuolar) adipocytes, immune cell infiltration, and microvascular density, to characterize tissue remodeling indicative of beige adipocyte induction.
Time frame: Baseline to Week 24
Correlation Between Different BAT Assessment Methods
Comparative analysis between 18F-FDG-PET/CT, MRI fat fraction, and infrared thermography for assessing BAT activity and volume.
Time frame: Baseline and Week 24
Change in Resting Energy Expenditure
Measured by indirect calorimetry using a portable metabolic analyzer. Outcome reported as absolute change in REE (kcal/day).
Time frame: Baseline to Week 24
Association Between Changes in Resting Energy Expenditure, Metabolic Health Markers, and Thermogenic Adipose Tissue
Assessed by evaluating correlations between changes in resting energy expenditure (REE, measured by indirect calorimetry), metabolic health parameters (including glucose metabolism, insulin sensitivity indices, lipid profile, and hormonal markers), body composition changes, and alterations in thermogenic adipose tissue activity and volume (as measured by 18F-FDG-PET/CT, MRI, and thermography). This outcome aims to determine the interrelationship between metabolic adaptations and thermogenic fat activation following tirzepatide treatment.
Time frame: Baseline to Week 24
Association Between Resting Energy Expenditure, Metabolic Health Markers, and Thermogenic Adipose Tissue
Assessed by evaluating correlations between anthropometric data, resting energy expenditure (REE, measured by indirect calorimetry), metabolic health parameters (including glucose metabolism, insulin sensitivity indices, lipid profile, and hormonal markers), body composition, and thermogenic adipose tissue activity and volume (as measured by 18F-FDG-PET/CT, MRI, and thermography). This outcome aims to determine variables that correlate with pre-treatment thermogenic adipose tissue quantity and activity.
Time frame: Baseline
Plan to share: Yes — De-identified individual participant data (IPD) to be shared will include demographic data, basic clinical measurements, body composition assessment, laboratory results, imaging data, resting energy expenditure measurements, molecular data and histological features from subcutaneous adipose tissue biopsies. All shared data will be fully de-identified, and no directly identifiable personal information will be included.
This study is completed, as verified in May 2025. You cannot join it, but the record below documents what was studied.
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University Medical Centre Ljubljana