Tirzepatide and Muscle Outcomes in Obesity

NCT07373834 | Recruiting

• 1 other identifier: TIRMO-0120-121/2025-2711-6
• Study Type: interventional
• Target: 30
• Locations: 1 country
• Sites: 1

Brief 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. 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)

Keywords

Obesity; Tirzepatide; Skeletal muscle; Muscle quality; Muscle mass; Muscle strength; Muscle function; Myosteatosis; Muscle transcriptomics

Outcome Measures

Primary Outcomes (2)

• Change in Body Mass and Composition

  Measured primarily as changes in body weight and body composition measured by dual-energy X-ray absorptiometry (DXA).

  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.

  Baseline to Week 24

Secondary Outcomes (5)

• Change in MRI-derived Skeletal Muscle Composition and Myosteatosis

  Baseline to Week 24

• Change in Molecular Markers in Vastus Lateralis Muscle: Gene-level Differential Expression

  Baseline to Week 24

• Change in Molecular Markers in Vastus Lateralis Muscle: Pathway-level Enrichment Analysis

  Baseline to Week 24

• Change in Intramyocellular Lipid Content (IMCL) in Vastus Lateralis Muscle

  Baseline to Week 24

• Change in the Muscle Fiber Diameter of Type I and Type II Fibers

  Baseline to Week 24

Other Outcomes (5)

• Change in Handgrip Strenght

  Baseline to Week 24

• Changes in Lower-Limb Functional Performance

  Baseline to Week 24

• Change in 6-Minute Walk Test (6MWT)

  Baseline to Week 24

Study Arms (2)

Tirzepatide

EXPERIMENTAL

Drug: Tirzepatide

Placebo

PLACEBO COMPARATOR

Drug: Placebo

Interventions

Placebo DRUG

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.

Placebo

Tirzepatide DRUG

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.

Tirzepatide

Eligibility Criteria

• Age: 18 Years - 50 Years
• Sex: female
• Healthy Volunteers: No
• Age Groups: Adult (18-64)

You may qualify if:

• 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

You may not qualify if:

• Sarcopenic obesity
• Pregnancy or lactation
• Postmenopausal status
• Diabetes
• Immobility
• Personal history of malignancy
• 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

Sponsors & Collaborators

• University Medical Centre Ljubljana: lead

Study Sites (1)

Department of Endocrinology, Diabetes and Metabolic Diseases, University Medical Centre Ljubljana

Ljubljana, 1000, Slovenia

RECRUITING

MeSH Terms

Conditions

Obesity

Interventions

Tirzepatide

Condition Hierarchy (Ancestors)

Overweight; Overnutrition; Nutrition Disorders; Nutritional and Metabolic Diseases; Body Weight; Signs and Symptoms; Pathological Conditions, Signs and Symptoms

Intervention Hierarchy (Ancestors)

Glucagon-Like Peptide-1 Receptor; Glucagon-Like Peptide Receptors; Receptors, G-Protein-Coupled; Receptors, Cell Surface; Membrane Proteins; Proteins; Amino Acids, Peptides, and Proteins; Receptors, Gastrointestinal Hormone; Receptors, Peptide

Study Officials

• Mojca Jensterle Sever, Prof.MD, PhD

  Department of Endocrinology, Diabetes and Metabolic Diseases, University Medical Centre Ljubljana

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Prof. Mojca Jensterle Sever, MD, PhD

CONTACT

0038631312977; mojca.jensterlesever@kclj.si

Andrijana Koceva, MD

CONTACT

0038630248963; andrijana_koceva@yahoo.com

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: DOUBLE
• Who Masked: PARTICIPANT, OUTCOMES ASSESSOR
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: December 5, 2025
• First Posted: January 28, 2026
• Study Start: January 1, 2026
• Primary Completion (Estimated): December 1, 2026
• Study Completion (Estimated): March 1, 2027
• Last Updated: January 28, 2026

Record last verified: 2025-11

Data Sharing

• IPD Sharing: Will share

Locations

SL (1)