Tirzepatide and Muscle Outcomes in Obesity

What Was Tested

This registered not phased trial tested Tirzepatide.

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.

It had two arms (groups): Tirzepatide (experimental) and Placebo (placebo comparator).

The registry classes the interventions as drug.

Who Took Part

30 planned participants were the target.

It was open to women only aged from 18 years up to 50 years.

Healthy volunteers were not accepted; participants needed the condition being studied.

Examples of who could join: Age between 18 and 50 years. BMI between 30 kg/m² and 40 kg/m². Commitment to use barrier contraception and absence of plans for pregnancy within 8 months following enrolment.

The full record lists 6 inclusion and 11 exclusion criteria; among the exclusions: sarcopenic obesity; pregnancy or lactation; postmenopausal status.

How the Study Was Run

Design: randomized, parallel-group and double-blind.

The participants were allocated by chance, so the Tirzepatide group and the comparison group should start out alike.

The Tirzepatide group and the comparison group ran side by side rather than switching.

As a double-blind Tirzepatide study, the assignments were hidden from both participants and investigators until the end.

Those kept unaware of assignments: participant and outcomes assessor.

It started in 2026-01 with completion listed for 2026-12.

It ran at 1 site in Slovenia.

Its stated primary purpose is treatment.

What Was Measured

Primary outcome: Change in Body Mass and Composition (time frame: Baseline to Week 24). Change in Quadriceps Muscle Strength (time frame: Baseline to Week 24).

It also tracked 5 secondary outcomes, for example Change in MRI-derived Skeletal Muscle Composition and Myosteatosis, Change in Molecular Markers in Vastus Lateralis Muscle: Gene-level Differential Expression, Change in Molecular Markers in Vastus Lateralis Muscle: Pathway-level Enrichment Analysis, Change in Intramyocellular Lipid Content (IMCL) in Vastus Lateralis Muscle and Change in the Muscle Fiber Diameter of Type I and Type II Fibers.

What This Means in Plain Language

Put simply, this is a not phased, randomized trial of Tirzepatide in 30 people.

Its size is small, so on its own it can only give an early look.

It is still recruiting; no results are posted to the registry yet, so nothing here describes outcomes.

More context: the Tirzepatide compound page, all human trials.