Breath Acetone During Tirzepatide Treatment and Resistance Training in Adults With Obesity (RESIST-EXHALE)

November 5, 2026 updated by: Technical University of Munich

Exhaled Breath Analysis for the Prediction of Treatment Response During Tirzepatide Therapy and Resistance Training in Adults With Obesity - An Ancillary Study to the RESIST Trial

This study is an ancillary study to the RESIST trial, in which adults with obesity receive the weight-loss medication tirzepatide and are randomly assigned to a structured resistance training program or to usual care for 24 weeks. RESIST-EXHALE measures acetone in exhaled breath, a non-invasive marker of fat burning, at all seven RESIST visits (Week 0 to Week 24). The study investigates how breath acetone changes during treatment, whether this change differs between participants with and without resistance training, and whether breath acetone at the start or early in treatment can predict the individual response to treatment, such as weight loss and preservation of muscle. The measurement takes about 15-20 minutes at the first visit and about 10 minutes at each later visit. No additional visits, interventions or biological samples are part of this ancillary study.

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.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

RESIST-EXHALE is a prospective, observational, monocentric ancillary study conducted at the TUM Klinikum, Munich, Germany. Active participation in the RESIST trial (protocol code RESIST-26-HAL-0150-I; EU CT number 2026-526200-69-00) is a prerequisite for enrolment. RESIST is a randomized, controlled, open-label Phase IV trial evaluating a structured resistance training program versus usual care in 150 adults with obesity treated with tirzepatide over 24 weeks.

RESIST-EXHALE involves no investigational medicinal product, no intervention and no randomization. Assignment to resistance training or usual care occurs exclusively within the RESIST trial. Breath acetone concentration is measured under standardized fasting conditions (at least 8 hours) at all RESIST visits (V1, Week 0; V2-V6, Weeks 4, 8, 12, 16, 20; V7, Week 24) using a handheld point-of-care breath acetone analyzer (Nutrion™, Alivion AG) with volume-controlled, end-tidal breath sampling. The device is used for research purposes only and does not inform clinical decisions. A short questionnaire on known confounders of breath acetone is completed before each measurement.

The primary endpoint is the change in breath acetone from V1 to V7, compared between arms. All analyses are exploratory and hypothesis-generating; no formal sample size calculation or multiplicity adjustment is performed.

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.
150

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.

Study Contact Backup

  • Name: Kristina Geyer, Dr. rer. nat.
  • Phone Number: +49 89 289 24925
  • Email: k.geyer@tum.de

Study Locations

  • Germany
      • München, Germany, 80809
        • TUM Klinikum, Department for Clinical Nutritional Medicine and Department for Preventive Sports Medicine and Sports Cardiology, Am Olympiacampus 11, 80809 Munich, Germany
        • Contact:

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

18 years to 60 years (Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Sampling Method

Non-Probability Sample

Study Population

Participants of the RESIST trial at the TUM Klinikum, Munich: adults aged 18-60 years with obesity (BMI ≥ 30 kg/m²) without manifest type 2 diabetes or structural cardiovascular disease, eligible for pharmacological weight-loss therapy and suitable for a structured resistance training program. Sufficient command of German is required.

Description

Inclusion Criteria:

  • Provisional eligibility for randomization into the RESIST trial (based on all RESIST screening assessments available at the time of informed consent for this ancillary study)
  • Written informed consent for this ancillary study

Exclusion Criteria:

  • Non-randomization into the RESIST trial for any reason
  • Any anatomical or functional condition preventing breath sampling through a mouthpiece (e.g., tracheostomy, laryngectomy, severe facial deformity), such that a valid end-tidal breath sample cannot be obtained

Key eligibility criteria of the RESIST trial (for context only; full criteria see RESIST protocol RESIST-26-HAL-0150-I):

  • Age 18-60 years
  • Obesity (BMI ≥ 30 kg/m²)
  • No manifest type 2 diabetes
  • No structural cardiovascular disease
  • Not pregnant or breastfeeding
  • Sufficient command of the German language

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

Group / Cohort

A group or subgroup of participants in an observational study that is assessed for biomedical or health outcomes.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Resistance training + tirzepatide

RESIST participants randomized to the structured resistance training arm of the RESIST trial, receiving tirzepatide and individualized diet and physical activity counselling. Assignment occurs within RESIST, not within this ancillary study.
Drug: Tirzepatide

Once-weekly subcutaneous injection over 24 weeks, starting at 2.5 mg/week and increased by 2.5 mg every 4 weeks as tolerated up to a maximum of 10 mg/week, in accordance with the SmPC. Administered within the RESIST trial (not part of this ancillary study).

Behavioral: Structured resistance training

Machine-based structured resistance training over 24 weeks, delivered within the RESIST trial (not part of this ancillary study). Progressive program with an acclimation phase (weeks 1-4) and a target phase (weeks 5-24; 8-12 repetitions at approx. 70-75% 1-RM, with additional eccentric overload from week 9). Sessions are intended to be fully supervised during the first 6 weeks whenever feasible, thereafter at least one supervised session after each interim visit; remaining sessions at the trial site or at partner fitness facilities.
Usual care + tirzepatide

RESIST participants randomized to the usual care arm of the RESIST trial, receiving tirzepatide and individualized diet and physical activity counselling. Assignment occurs within RESIST, not within this ancillary study.
Drug: Tirzepatide

Once-weekly subcutaneous injection over 24 weeks, starting at 2.5 mg/week and increased by 2.5 mg every 4 weeks as tolerated up to a maximum of 10 mg/week, in accordance with the SmPC. Administered within the RESIST trial (not part of this ancillary study).

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 breath acetone concentration from baseline to end of treatment
Time Frame: Baseline (Week 0) and end of treatment (Week 24)

Breath acetone concentration (ppm) measured under standardized fasting conditions with a handheld point-of-care breath acetone analyzer. Change from baseline to Week 24, compared between the resistance training group and the usual care group, adjusted for baseline.
Baseline (Week 0) and end of treatment (Week 24)

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
Baseline breath acetone and change in body weight
Time Frame: Baseline (Week 0) to Week 24

Regression coefficient of the percentage change in body weight (%; calibrated scale) on baseline breath acetone (ppm; handheld breath acetone analyzer)
Baseline (Week 0) to Week 24
Baseline breath acetone and change in fat mass
Time Frame: Baseline (Week 0) to Week 24

Regression coefficient of the change in fat mass (kg; bioelectrical impedance analysis) on baseline breath acetone (ppm; handheld breath acetone analyzer)
Baseline (Week 0) to Week 24
Baseline breath acetone and change in skeletal muscle mass
Time Frame: Baseline (Week 0) to Week 24

Regression coefficient of the change in skeletal muscle mass (kg; bioelectrical impedance analysis) on baseline breath acetone (ppm; handheld breath acetone analyzer)
Baseline (Week 0) to Week 24
Baseline breath acetone and change in thigh muscle volume
Time Frame: Baseline (Week 0) to Week 24

Regression coefficient of the change in contractile thigh muscle volume (mL; MRI) on baseline breath acetone (ppm; handheld breath acetone analyzer)
Baseline (Week 0) to Week 24
Baseline breath acetone and change in knee extension strength
Time Frame: Baseline (Week 0) to Week 24

Regression coefficient of the change in peak isometric knee extension torque (Nm; isokinetic dynamometer) on baseline breath acetone (ppm; handheld breath acetone analyzer)
Baseline (Week 0) to Week 24
Change in breath acetone concentration from baseline to Week 4
Time Frame: Baseline (Week 0) and Week 4

Breath acetone concentration (ppm; handheld breath acetone analyzer) under standardized fasting conditions; change from Week 0 to Week 4, compared between groups
Baseline (Week 0) and Week 4
Time course of breath acetone concentration during treatment
Time Frame: Week 0 to Week 24

Breath acetone concentration (ppm; handheld breath acetone analyzer) at Weeks 0, 4, 8, 12, 16, 20 and 24, compared between groups
Week 0 to Week 24
Predictive value of early change versus baseline breath acetone for clinical response
Time Frame: Baseline (Week 0) to Week 24

Comparative predictive value of the change in breath acetone concentration from Week 0 to Week 4 versus the baseline (Week 0) breath acetone concentration alone (ppm; handheld breath acetone analyzer) for the percentage change in body weight (%; calibrated scale) from Week 0 to Week 24 (RESIST data).
Baseline (Week 0) to Week 24
Baseline breath acetone and change in handgrip strength
Time Frame: Baseline (Week 0) to Week 24

Regression coefficient of the change in maximum handgrip strength (kg; hand dynamometer) on baseline breath acetone (ppm; handheld breath acetone analyzer)
Baseline (Week 0) to Week 24

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.
Technical University of Munich

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.
October 22, 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.
July 31, 2027

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.
July 31, 2027

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).
October 17, 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.
  • 2026-537-S-CT

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

Individual participant data will not be shared outside the sponsor institution. Aggregated or fully anonymized data may be made available to researchers upon reasonable request to the Principal Investigator.

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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