The Impact of Incretins on Fat-free Mass, Muscle Strength and Functional Capacity (IMPACT)

November 5, 2026 updated by: Maria Hopman, Radboud University Medical Center

Uncovering the Impact of Incretins on Fat-free Mass, Muscle Strength and Functional Capacity: an Observational Prospective Cohort

The goal of this observational study is to learn how treatment with incretins, such as semaglutide and tirzepatide, affects muscle mass, muscle strength, and physical function in people with overweight or obesity.

The main questions this study aims to answer are:

  • What is the composition of weight loss during incretin treatment?
  • What is the composition of recurrent weight gain after stopping incretin treatment?

An additional question this study aims to answer is:

- How do muscle strength and physical function change during and after incretin treatment?

Two groups of patients will be included: patients who start with incretin therapy for overweight/obesity and patients who stop incretin therapy for overweight/obesity.

Participants who start incretin treatment will have measurements before starting treatment, after six months, and after twelve months or when treatment is stopped. Participants who stop incretin treatment will have measurements before stopping treatment, after six months, and after twelve months or before restarting treatment.

Measurements include:

  • Height, length, waist circumference
  • Body composition measured with InBody, with a Dual-Energy X-ray Absorptiometry in a subgroup of the participants
  • Muscle strength tests
  • Physical function tests
  • Blood samples to asses metabolic health
  • Physical activity measured with an activity monitor (ActivPAL)
  • Questionnaires about health, incretin treatment, physical activity, and diet

No treatment or medication will be given as part of the study. Participants will receive incretin treatment as part of their usual care.

Study Overview

Status

Recruiting

Conditions

Study Type

Observational

Enrollment (Estimated)

200

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 Backup

Study Locations

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

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Sampling Method

Non-Probability Sample

Study Population

People with overweight or obesity

Description

Inclusion Criteria:

  • Screened and planned to start with incretin treatment or currently using incretin and planned to discontinue treatment.
  • Aged 18 years or older

Exclusion Criteria:

  • Inability to comprehend scheduled procedures (e.g., language barriers)
  • Unable to perform the physical tests due to physical disabilities
  • Patients who underwent MBS or including endoscopic interventions and gastric balloon placement.
  • Prior use of incretins, or other obesity medication.

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: PROSPECTIVE

Cohorts and Interventions

Group / Cohort
START-group

Participants who start with incretin treatment
STOP-group

Participants who stop with incretin treatment

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
The composition of weight loss during treatment
Time Frame: 12 months

Ratio of fat-free mass (FFM) to total weight loss. FFM will be measured using a InBody Bioelectrical Impedance Analysis (BIA) and a Dual-Energy X-ray Absorptiometry (in a subgroup).
12 months
The composition of recurrent weight gain after cessation of treatment
Time Frame: 12 months

The ratio of fat-free mass (FFM) to recurrent weight gain. FFM will be measured using a InBody Bioelectrical Impedance Analysis (BIA) and a Dual-Energy X-ray Absorptiometry (in a subgroup).
12 months

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Muscle strength
Time Frame: 12 months

Maximal handgrip strength will be measured using a hand dynamometer. An isometric strength test will be used to determine maximum strength and maximum power using a leg extension machine.
12 months
Functional capacity
Time Frame: 12 months

The Four Metre Walk Test and the Timed Chair-Stand_test will be performed to determine functional capacity.
12 months

Other Outcome Measures

Outcome Measure
Measure Description
Time Frame
Physical activity patterns
Time Frame: 12 months

Habitual physical activity patterns will be objectively measured with a validated accelerometer.
12 months
(Cardio)metabolic health
Time Frame: 12 months

Non-fasted venous blood samples will be drawn to provide information on glycated hemoglobin (HbA1c), lipid profile (Total Cholesterol, HDL Cholesterol, LDL Cholesterol, Triglycerides), high-sensitivity C-reactive protein (hs-CRP) and creatine kinase (CK).
12 months
Performance of resistance training
Time Frame: 12 months

The performance of muscle resistance training will be assessed using the Muscle-Strengthening Exercise Questionnaire (MSEQ).
12 months
Protein intake
Time Frame: 12 months

Habitual dietary (protein) intake will be assessed using a Food Frequency Questionnaire (FFQ), a validated dietary assessment tool.
12 months

Collaborators and Investigators

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

Sponsor

Radboud University Medical Center

Collaborators

ZonMw: The Netherlands Organisation for Health Research and Development

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 (Actual)

August 28, 2026

Primary Completion (Estimated)

February 1, 2027

Study Completion (Estimated)

March 1, 2027

Study Registration Dates

First Submitted

October 29, 2026

First Submitted That Met QC Criteria

November 5, 2026

First Posted (Actual)

November 10, 2026

Study Record Updates

Last Update Posted (Actual)

November 10, 2026

Last Update Submitted That Met QC Criteria

November 5, 2026

Last Verified

September 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • NL-011099

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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