An observational study in Obesity & Overweight, sponsored by Ulsan University Hospital. Not yet recruiting. Open to participants aged 19 Years and older, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-11-12.
Sponsored by Ulsan University Hospital · Observational
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.
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.
11,522 studies on the registry are indexed under Obesity; 2,033 are open to participants now.
This study's planned enrollment of 240 is above the median of 114 across 2,154 observational studies indexed under Obesity.
Browse Obesity studies →Ulsan University Hospital is the lead sponsor of 29 studies on the registry; 8 are open to participants now.
Counted across the registry records on this site, refreshed daily.
; 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
## Inclusion criteria [Prospective GLP-1RA treatment cohort]
[Retrospective Matched Control cohort]
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]
[Retrospective Matched Control cohort]
∙ Individuals with insufficient abdominal CT images or clinical data for evaluating longitudinal changes in body composition.
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
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.
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.
Change in the Ratio of Low-attenuation Muscle Area to Total abdominal muscle area (LAMA/TAMA Ratio)
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
Time frame: Baseline to approximately 12±6 months after GLP-1RA treatment initiation
Change in Total abdominal muscle area (TAMA)
Change in total abdominal muscle area, measured using non-contrast abdominal CT at the L3 level
Time frame: Baseline to approximately 12±6 months after GLP-1RA treatment initiation
Change in Visceral Fat Area (VFA)
Change in visceral fat area, measured using non-contrast abdominal CT at the L3 level.
Time frame: Baseline to approximately 12±6 months after GLP-1RA treatment initiation
Change in Subcutaneous Fat Area (SFA)
Change in subcutaneous fat area, measured using non-contrast abdominal CT at the L3 level.
Time frame: Baseline to approximately 12±6 months after GLP-1RA treatment initiation
Change in Handgrip Strength
Change in maximal handgrip strength, assessed using a hand dynamometer at baseline and follow-up.
Time frame: Baseline to approximately 12±6 months after GLP-1RA treatment initiation
No study locations are listed for this record.
Plan to share: Undecided — 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.
No publications or documents are linked to this record.
Start is estimated for Nov 2026; primary completion for Aug 2028, 21 months later.
Of 791 non-industry observational studies under Obesity, half reached primary completion within 40 months of starting (the median), counting those still running; a quarter within 17 and three quarters within 106. This study's planned 21 months is below that.
Counting every sponsor, half of 836 studies reached it within 39 months; a quarter within 17 and three quarters within 96.
How these figures are worked out, and which studies are left out of them.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is not yet recruiting, as verified in Nov 2026. You cannot join it, but the record below documents what was studied.
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Ulsan University Hospital