Obesity (Disorder)TIRMONCT07373834
Tirzepatide and Muscle Outcomes in Obesity
A study testing Tirzepatide in people with Obesity (Disorder), run by University Medical Centre Ljubljana at 1 site in Slovenia.
Trial summary
This study is evaluating whether a dual glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) receptor agonist, tirzepatide, can affect the function, structure and metabolism of skeletal muscles in adults with obesity. Read more about this study
- Who is it for?
- Ages 18 to 50 years, women only
- Conditions the study is for
- Obesity (Disorder)
- What is being tested?
- Tirzepatide
- Type of treatment
- Injection or infusion
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 30 participants
- Where
- 1 siteSlovenia
- Study dates
- Jan 2026to Mar 2027
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 50 years
- Women only
- No healthy volunteers
- Adult
Who may be able to join
- Female sex
- Age between 18 and 50 years
- BMI between 30 kg/m² and 40 kg/m²
- Stable body weight within the three months preceding study enrolment (defined as ≤ 5% change)
- No prior pharmacological or surgical interventions for obesity treatment
- Commitment to use barrier contraception and absence of plans for pregnancy within 8 months following enrolment
Who cannot join
- Sarcopenic obesity
- Pregnancy or lactation
- Postmenopausal status
- Diabetes
- Immobility
- Personal history of malignancy
Show all 11Show fewer
- Personal history of pancreatitis
- Personal history of major depressive episodes
- Personal history of myopathy
- Personal or family history of medullary thyroid carcinoma
- Current treatment with metformin or systemic corticosteroids
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Slovenia1 site, 1 recruiting
- Recruiting
Department of Endocrinology, Diabetes and Metabolic Diseases, University Medical Centre Ljubljana
Ljubljana, 1000
Prof. Andrej Janež, MD, PhD, 0038615223564, andrej.janez@kclj.si
Prof. Mojca Jensterle Sever, MD, PhD
About this study
Official title: Effects of Tirzepatide on Skeletal Muscle in Obesity
This study is evaluating whether a dual glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) receptor agonist, tirzepatide, can affect the function, structure and metabolism of skeletal muscles in adults with obesity. Participants, premenopausal females with obesity, will receive either tirzepatide or placebo over 24 weeks. Researchers will assess body weight, body composition, muscle strength and functional performance, neuromuscular function and will perform muscle biopsies before and after treatment to study molecular and histological changes following treatment. The goal of this study is to investigate the effects of tirzepatide on skeletal muscle function, quantity, quality and metabolism in adults with obesity as well as clarify the molecular and structural adaptations in skeletal muscle during tirzepatide-induced weight loss, addressing an important gap in understanding the impact of incretin-based therapies on muscle health.
- Conditions
- Obesity (Disorder)
- Being tested
- Tirzepatide, Placebo
- Keywords
- Obesity, Tirzepatide, Skeletal muscle, Muscle quality, Muscle mass, Muscle strength, Muscle function, Myosteatosis, Muscle transcriptomics
- Medical subject headings
- Obesity
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
TirzepatideDrug
Tirzepatide is a dual glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) 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.
PlaceboDrug
Placebo (saline solution) will be administered via subcutaneous injection once weekly with dose escalation following the same schedule (2.5 mg equivalent increments every 4 weeks) to preserve blinding integrity.
| Study group | Role | What they receive |
|---|---|---|
| Tirzepatide | Experimental | Not described Receives: Drug: Tirzepatide |
| Placebo | Placebo comparator | Not described Receives: Drug: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in Body Mass and Composition
Measured primarily as changes in body weight and body composition measured by dual-energy X-ray absorptiometry (DXA).
Measured: Baseline to Week 24
Change in Quadriceps Muscle Strength
Change in maximal knee extensor torque normalized to body mass (Nm/kg) will be evaluated using an isokinetic dynamometer.
Measured: Baseline to Week 24
Secondary outcomes (5)
Change in MRI-derived Skeletal Muscle Composition and Myosteatosis
Muscle volume and muscle fat fraction will be quantified using magnetic resonance imaging (MRI).
Measured: Baseline to Week 24
Change in Molecular Markers in Vastus Lateralis Muscle: Gene-level Differential Expression
Transcriptome-wide RNA-sequencing will be performed on vastus lateralis muscle biopsies from all participants (depending on sample quality and RNA integrity) before and after the intervention to identify differentially expressed genes associated with tirzepatide treatment. Differential gene expression will be reported as log2 fold change (log2FC) between post and pre-intervention, derived from normalized RNA-sequencing read counts. Statistical significance will be summarized using false discovery rate (FDR)-adjusted p-values.
Measured: Baseline to Week 24
Change in Molecular Markers in Vastus Lateralis Muscle: Pathway-level Enrichment Analysis
Pathway-level changes will be reported using normalized enrichment scores (NES) derived from gene set enrichment analysis (GSEA), together with false discovery rate (FDR)-adjusted q-values for biological processes including mitochondrial function, lipid metabolism, insulin signaling, inflammation, muscle atrophy, and myogenesis.
Measured: Baseline to Week 24
Change in Intramyocellular Lipid Content (IMCL) in Vastus Lateralis Muscle
Assessed by Oil Red O staining using a standard protocol. IMCL will be quantified as the proportion of Oil Red O-positive area per fibre and averaged across available fibres per section per time point. Microscopy imaging and analysis settings will be kept consistent across time points, and assessors will be blinded to group/time.
Measured: Baseline to Week 24
Change in the Muscle Fiber Diameter of Type I and Type II Fibers
Muscle fiber diameter will be measured on the biopsy section using routine light microscopy. Fiber typing (type 1 vs type 2) will be performed by standard immunohistochemistry for myosin heavy chain isoforms. The metric is mean minimal Feret diameter in micrometers, averaged across available fibers of same type.
Measured: Baseline to Week 24
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted28 Jan 2026
- Study startJan 2026 (estimated)
- Primary completionDec 2026 (estimated)
- Study completionMar 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Obesity (Disorder)Studies of the same condition, open and under way.
- More trials run by University Medical Centre LjubljanaThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind
- Who is masked
- Participant, Outcomes assessor
- Enrolment
- 30 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University Medical Centre Ljubljana
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- Mojca Jensterle Sever, Prof.MD, PhD, Principal investigator, Department of Endocrinology, Diabetes and Metabolic Diseases, University Medical Centre Ljubljana
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07373834
- Sponsor's protocol ID
- TIRMO-0120-121/2025-2711-6
- Acronym
- TIRMO
- Status last verified
- Nov 2025
- First submitted
- 5 Dec 2025
- Last updated
- 28 Jan 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: De-identified individual participant data (IPD) to be shared will include demographic data, basic clinical measurements, body composition assessment, laboratory results, muscle strength and function assessment data, molecular data and histological features from skeletal muscle biopsies. All shared data will be fully de-identified, and no directly identifiable personal information will be included.
Study at a glance
From the registry record, last updated by the sponsor on 28 Jan 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effects of Tirzepatide on Skeletal Muscle in Obesity
- ClinicalTrials.gov ID
- NCT07373834
- Acronym / sponsor ID
- TIRMO / TIRMO-0120-121/2025-2711-6
- Conditions
- Obesity (Disorder)
- Keywords
- Obesity, Tirzepatide, Skeletal muscle, Muscle quality, Muscle mass, Muscle strength, Muscle function, Myosteatosis
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 30 participants (estimated)
- Lead sponsor
- University Medical Centre LjubljanaUniversity, hospital or other
- Study start
- Jan 2026 (estimated)
- Primary completion
- Dec 2026 (estimated)
- Study completion
- Mar 2027 (estimated)
- First posted
- 28 Jan 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This study is evaluating whether a dual glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) receptor agonist, tirzepatide, can affect the function, structure and metabolism of skeletal muscles in adults with obesity. Participants, premenopausal females with obesity, will receive either tirzepatide or placebo over 24 weeks. Researchers will assess body weight, body composition, muscle strength and functional performance, neuromuscular function and will perform muscle biopsies before and after treatment to study molecular and histological changes following treatment. The goal of this study is to investigate the effects of tirzepatide on skeletal muscle function, quantity, quality and metabolism in adults with obesity as well as clarify the molecular and structural adaptations in skeletal muscle during tirzepatide-induced weight loss, addressing an important gap in understanding the impact of incretin-based therapies on muscle health.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind (participant, outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Tirzepatide | Experimental | Drug: Tirzepatide |
| Placebo | Placebo comparator | Drug: Placebo |
Who may qualify
- Ages
- 18 to 50 years
- Sex
- Female only
- Healthy volunteers
- Not accepted
- Age groups
- Adult
Key inclusion criteria (6 listed)
- Female sex
- Age between 18 and 50 years
- BMI between 30 kg/m² and 40 kg/m²
- Stable body weight within the three months preceding study enrolment (defined as ≤ 5% change)
- No prior pharmacological or surgical interventions for obesity treatment
Key exclusion criteria (11 listed)
- Sarcopenic obesity
- Pregnancy or lactation
- Postmenopausal status
- Diabetes
- Immobility
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| TirzepatideTirzepatide is a dual glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) 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. | Drug | Tirzepatide |
| PlaceboPlacebo (saline solution) will be administered via subcutaneous injection once weekly with dose escalation following the same schedule (2.5 mg equivalent increments every 4 weeks) to preserve blinding integrity. | Drug | Placebo |
Primary outcome
Change in Body Mass and Composition
Time frame: Baseline to Week 24
Measured primarily as changes in body weight and body composition measured by dual-energy X-ray absorptiometry (DXA).
Change in Quadriceps Muscle Strength
Time frame: Baseline to Week 24
Change in maximal knee extensor torque normalized to body mass (Nm/kg) will be evaluated using an isokinetic dynamometer.
5 secondary outcomes
Change in MRI-derived Skeletal Muscle Composition and Myosteatosis
Time frame: Baseline to Week 24
Change in Molecular Markers in Vastus Lateralis Muscle: Gene-level Differential Expression
Time frame: Baseline to Week 24
Change in Molecular Markers in Vastus Lateralis Muscle: Pathway-level Enrichment Analysis
Time frame: Baseline to Week 24
Change in Intramyocellular Lipid Content (IMCL) in Vastus Lateralis Muscle
Time frame: Baseline to Week 24
Change in the Muscle Fiber Diameter of Type I and Type II Fibers
Time frame: Baseline to Week 24
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 28 Jan 2026.
- Individual participant dataSharing planned: Yes. De-identified individual participant data (IPD) to be shared will include demographic data, basic clinical measurements, body composition assessment, laboratory results, muscle strength and function assessment data, molecular data and histological features from skeletal muscle biopsies. All shared data will be fully de-identified, and no directly identifiable personal information will be included.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Mojca Jensterle Sever, Prof.MD, PhD principal investigator
Department of Endocrinology, Diabetes and Metabolic Diseases, University Medical Centre Ljubljana
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Tirzepatide in people with Obesity (Disorder), run by University Medical Centre Ljubljana at 1 site in Slovenia.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 6 inclusion and 11 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 28 Jan 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Slovenia. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Prof. Mojca Jensterle Sever, MD, PhD (0038631312977, mojca.jensterlesever@kclj.si), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in Body Mass and Composition (time frame: Baseline to Week 24). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 28 Jan 2026.