Changes in Body Composition and Muscle Composition After GLP-1 Receptor Agonist Therapy in Patients With Obesity

November 5, 2026 updated by: Mi-Hee Jang, Ulsan University Hospital

Changes in Body Composition and Muscle Composition After GLP-1 Receptor Agonist Therapy in Patients With Obesity; A CT-Based Longitudinal Study

This study aims to evaluate changes in body composition and skeletal muscle composition following glucagon-like peptide-1 receptor agonist (GLP-1RA) therapy in adults with obesity or overweight with weight-related comorbidities. Ulsing computed tomography (CT), the study will quantitatively assess changes in skeletal muscle quantity, muscle attenuation, and adipose tissue distribution before and after treatment.

This is a single-center observational study consisting of a prospective GLP-1RA treatment cohort and a retrospective matched control cohort. A total of 240 participants will be included, comprising 120 patients receiving GLP-1RA therapy and 120 matched controls. The study aims to clarify whether changes in body composition following GLP-1 RA therapy reflect reductions in skeletal muscle quantity, changes in muscle composition, or both.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Detailed Description

Obesity is a major risk factor for metabolic and cardiovascular diseases. GLP-1 receptor agonists, including semaglutide and tirzepatide, have demonstrated substantial weight-reducing effects and are increasingly used in clinical practice. However, the effects of GLP-1 RA therapy on skeletal muscle quantity and quality remain incompletely understood.

Previous studies using dual-energy X-ray absorptiometry or bioelectrical impedance analysis have reported reductions in lean mass following GLP-1RA therapy. Nevertheless, lean mass includes non-muscle components, and these methods have limitations in distinguishing skeletal muscle tissue from intramuscular or intermuscular adipose tissue.

CT-based body composition analysis allows quantitative assessment of skeletal muscle area, muscle attenuation, and adipose tissue distribution. This study will evaluate changes in these parameters at the third lumbar vertebral level (L3) before and approximately 12 ± 6 months after GLP-1RA treatment initiation.

The prospective cohort will include 120 adults who are newly prescribed GLP-1RA therapy as part of routine clinical care at Ulsan University Hospital. Participants will undergo non-contrast CT examinations at baseline and follow-up. Clinical measurements, laboratory findings, handgrip strength will also be assessed. In addition, questionnaire-based assessments of quality of life, physical activity, depression, and anxiety will be conducted as specified in the study protocol.

A retrospective control cohort of 120 adults who previously underwent health examinations and had at least two CT scans separated by one year or longer will bel selected. Controls will be matched to the treatment cohort by age, sex, and body mass index.

The primary outcomes are changes in the ratio of low-attenuation muscle area to total abdominal muscle area and extramyocellular lipid area. Secondary outcomes include changes in total abdominal muscle area, visceral and subcutaneous fat area, anthropometric measurements, and other clinical parameters.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Observational

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
240

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

19 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

All

Sampling Method

Non-Probability Sample

Study Population

; Adults aged 19 years or older receiving clinical care at Ulsan University Hospital will be included. The prospective treatment cohort will consist of patients with obesity or overweight with at least one weight-related comorbidity who are newly prescribed GLP-1RA therapy. The retrospective control cohort will consist of adults who underwent health examinations and had at least two abdominal CT examinations separated by at least one year. Controls will be matched to treated patients according to age, sex, and BMI

Description

## Inclusion criteria [Prospective GLP-1RA treatment cohort]

  • Adults aged 19 years or older.
  • Patients with a BMI ≥30 kg/㎡, or a BMI ≥27 kg/㎡ and < 30 kg/㎡ with at least one weight-related comorbidity.
  • Patients for whom GLP-1 RA therapy has been initiated or planned based on clinical judgement.
  • Patients who voluntarily provide written informed consent to participate in the study.

[Retrospective Matched Control cohort]

  • Adults aged 19 years or older who underwent health examinations at Ulsan University Hospital

  • Individuals who underwent at least two abdominal computed tomography (CT) examinations separated by an interval of at least one year.

    ## Exclusion criteria [Prospective GLP-1RA treatment cohort]

  • Patients who are unable to undergo follow-up CT examinations.

  • Patients who are unable to continue GLP-1 RA therapy during the study period.

  • Patients with severe medical conditions that may substantially affect skeletal muscle mass or body composition.

[Retrospective Matched Control cohort]

∙ Individuals with insufficient abdominal CT images or clinical data for evaluating longitudinal changes in body composition.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Observational Models: COHORT
  • Time Perspectives: OTHER

Cohorts and Interventions

Group / Cohort

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
Group 1 - GLP-1 RA treatment cohort

Adults with obesity with weight-related comorbidities who initiate GLP-1RA therapy as part of routine clinical care. Participants will undergo non-contrast CT examinations at baseline and approximately 12±6 months after treatment initiation. Body composition, muscle composition, and relevant clinical parameters will be assessed longitudinally.
Retrospective Matched Control Cohort

Adults who previously underwent health examinations at Ulsan University Hospital and had at least two abdominal CT scans separated by at least one year. Participants will be retrospectively selected and matched 1:1 to the GLP-1 RA treatment cohort according to age, sex, and BMI. Existing CT images and clinical records will be used to evaluate longitudinal changes in body composition.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Change in the Ratio of Low-attenuation Muscle Area to Total abdominal muscle area (LAMA/TAMA Ratio)
Time Frame: Baseline to approximately 12±6 months after GLP-1RA treatment initiation

Change in the percentage of low-attenuation muscle area relative to total abdominal muscle area, measured using non-contrast abdominal CT at the third lumbar vertebra level
Baseline to approximately 12±6 months after GLP-1RA treatment initiation

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Change in Total abdominal muscle area (TAMA)
Time Frame: Baseline to approximately 12±6 months after GLP-1RA treatment initiation

Change in total abdominal muscle area, measured using non-contrast abdominal CT at the L3 level
Baseline to approximately 12±6 months after GLP-1RA treatment initiation
Change in Visceral Fat Area (VFA)
Time Frame: Baseline to approximately 12±6 months after GLP-1RA treatment initiation

Change in visceral fat area, measured using non-contrast abdominal CT at the L3 level.
Baseline to approximately 12±6 months after GLP-1RA treatment initiation
Change in Subcutaneous Fat Area (SFA)
Time Frame: Baseline to approximately 12±6 months after GLP-1RA treatment initiation

Change in subcutaneous fat area, measured using non-contrast abdominal CT at the L3 level.
Baseline to approximately 12±6 months after GLP-1RA treatment initiation
Change in Handgrip Strength
Time Frame: Baseline to approximately 12±6 months after GLP-1RA treatment initiation

Change in maximal handgrip strength, assessed using a hand dynamometer at baseline and follow-up.
Baseline to approximately 12±6 months after GLP-1RA treatment initiation

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Ulsan University Hospital

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
November 1, 2026

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
August 1, 2028

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
August 1, 2028

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
November 5, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 5, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
November 12, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
November 12, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
November 5, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
November 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • UUH 2026-09-050-001

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

IPD Plan Description

It is currently undecided whether individual participant data will be shared. Any future data sharing will be subject to institutional policies, ethical considerations, and applicable regulations.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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