Resistance Training to Preserve Thigh Muscle Volume in Adults with Obesity Treated with Tirzepatide (Phase IV Randomized Trial)

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What is this study about?

Adults with Obesity are being studied; this condition refers to having excess body weight that can increase the risk of health problems. The medication used is tirzepatide, a drug given as a small shot under the skin (subcutaneous injection) that helps lower blood sugar and often leads to weight loss. In addition to the medication, participants may follow a program of resistance training, which involves exercises that use weights or other resistance to strengthen muscles.

The purpose of the study is to see whether the exercise program can reduce loss of thigh muscle while participants receive tirzepatide. Participants will receive the medication once a week, with the dose possibly increasing over time, and will either join the structured resistance‑training sessions or continue with their usual care. The study will last several months, with regular visits to check weight, strength, and overall health.

During the study, muscle size will be measured using magnetic resonance imaging, a type of scan that creates detailed pictures of the body without radiation, and strength will be tested with simple devices that measure how hard the leg can push or how strong the hand grip is. Additional checks will include weighing on a calibrated scale, questionnaires about quality of life, and activity monitoring with a small wearable device. All procedures are planned to be straightforward and non‑invasive.

1 enrollment confirmation

after you agree to join the study, you will receive a confirmation that you are now a participant.

the study staff will give you an overview of what will happen during the trial.

2 baseline assessments

you will undergo an initial set of measurements before any treatment starts.

these include a magnetic resonance imaging (mri) scan of your thighs to measure muscle volume, a weight measurement on a calibrated scale, and tests of your knee strength, handgrip strength, and ability to stand up from a chair.

you will also complete questionnaires about your quality of life, mood, and daily physical activity.

3 start of tirzepatide injections

you will begin receiving tirzepatide, a medication that is injected under the skin (subcutaneous injection) using a pre‑filled KwikPen.

the pens are available in four strengths: 2.5 mg, 5 mg, 7.5 mg, and 10 mg per dose.

you will be instructed to give yourself one injection each week, using the dose that the study team prescribes for you.

the weekly injections will continue for the entire study period, which lasts until the final study visit in march 2027.

4 resistance training program (experimental group only)

if you are assigned to the resistance‑training group, you will follow a supervised exercise program designed to keep thigh muscles from shrinking.

the program consists of three training sessions per week, each lasting about 45 minutes and focusing on leg and lower‑body exercises.

sessions are recorded automatically by the training devices, and the data are used to track how many sessions you complete each week.

5 monthly follow‑up visits

once a month you will return to the clinic for a safety check and to review your progress.

during each visit the staff will count the used injection pens to verify how many doses you have taken, measure your weight, and ask about any side effects.

if you are in the training group, the staff will also review your training logs.

6 mid‑study assessments

approximately halfway through the trial (around 12 weeks after starting), you will undergo a second set of mri scans of the thighs and other body regions, repeat the strength tests, and complete the questionnaires again.

these measurements help compare changes from the start of the study.

7 final assessment

at the end of the study (march 2027) you will have a comprehensive visit that repeats all baseline measurements: mri scans, weight, strength tests, and questionnaires.

the study team will also collect the remaining injection pens and training device data.

8 study completion

after the final visit, you will be instructed on how to stop the weekly injections and, if applicable, how to transition off the structured resistance‑training program.

the study will be officially concluded for you, and no further study‑related procedures are required.

Who Can Join the Study?

You are at least 18 years old and not older than 60 years old.
Your BMI (body‑mass index, a number that compares weight to height) is 30 or higher.
You have tried at least one diet on your own that did not help you lose weight.
You are motivated, able, and willing to learn how to give yourself an injection of the study medication (self‑injection), to give the injections as instructed, and to follow all study visits, the resistance‑training program (if assigned), and lifestyle recommendations.
If you are a woman who could become pregnant, you must either (a) have no sexual contact with men (or be in a same‑sex relationship) and stay that way until 30 days after the last injection, or (b) have a negative pregnancy test and agree to use reliable birth control (a method that fails less than 1 % of the time, or two methods together) from the start of the study until 30 days after the last injection.
You can understand German well enough to follow the study instructions and read the consent information.
You are able to sign a written informed consent form.

Who Cannot Join the Study?

Having Type 1 Diabetes or a past history of Type 2 Diabetes (even if it seemed to be gone), or having had ketoacidosis, a hyperosmolar hyperglycaemic state, or a diabetes‑related coma.
Having very high blood pressure that is not controlled (systolic ≥ 160 mmHg or diastolic ≥ 100 mmHg), also called uncontrolled hypertension.
Having vision, nerve, muscle, or joint problems that would stop you from safely doing the exercise program or giving yourself the study medication on your own.
Having kidney disease with an estimated glomerular filtration rate (eGFR) below 30 mL/min/1.73 m² (a measure of how well the kidneys filter waste).
Having a serious stomach‑emptying disorder such as severe gastroparesis (stomach does not empty properly) or a blockage, or regularly taking medicines that change how the gut moves.
Having a history of pancreatitis (inflammation of the pancreas), either acute or chronic.
Having a thyroid‑stimulating hormone (TSH) level outside the normal range of 0.4 to 6.0 mIU/L.
Having a significant or unstable mental health condition such as major depression, schizophrenia, bipolar disorder, or other severe psychiatric illness within the past two years.
Scoring 15 or higher on the PHQ‑9 questionnaire, which measures depression severity.
Having current suicidal thoughts or actions as identified by the suicide‑risk questionnaire (C‑SSRS).
Having ever attempted suicide or shown suicidal behavior in the past (excluding non‑suicidal self‑injury).
Having lab results that indicate diabetes: glycated hemoglobin A1c (HbA1c) ≥ 6.5% or fasting blood sugar ≥ 126 mg/dL.
Having active liver disease such as hepatitis, or liver enzyme levels that are very high (ALT > 3 times the normal limit or bilirubin > 1.5 times normal), except mild fatty liver disease.
Having a family or personal history of medullary thyroid carcinoma or multiple endocrine neoplasia type 2, or a high blood level of calcitonin (a hormone marker).
Having an active or untreated cancer, or being in remission from a serious cancer for less than five years (excluding certain skin cancers and early‑stage cervical or prostate cancers).
Having a substance use problem, an eating disorder, or another psychiatric condition that might make it hard to follow the study rules.
Having received an organ transplant (except a cornea transplant) or currently waiting for one.
Having blood disorders that could affect the accuracy of the HbA1c test, such as hemolytic anemia or sickle cell disease.
Having any other medical problem that, according to doctors, makes moderate‑to‑high intensity resistance training unsafe (for example, active eye disease, unstable heart, nerve, or muscle conditions).
Having previously taken a GLP‑1 receptor agonist or a dual incretin receptor agonist medication at any time.
Currently taking, or having taken in the past three months, long‑term systemic steroids (more than 14 days) or having an active autoimmune disease (like lupus or rheumatoid arthritis) that may need steroid treatment.
Having used medicines that cause significant weight gain within the past three months (such as certain antidepressants, antipsychotics, or mood stabilizers).
Having unintentionally lost more than 5 kg (about 11 lb) of body weight in the three months before screening.
Having taken weight‑loss drugs or supplements (other than GLP‑1 medicines) in the past three months.
Being enrolled in another clinical study that is not compatible with this trial.
Having participated in another clinical trial within the last 30 days (or longer if the previous drug’s half‑life requires).
Having done a structured resistance‑training program (at least twice a week for four weeks) in the past three months.
Having any reason that makes an MRI unsafe, such as metal implants, severe claustrophobia, or a body size that exceeds the scanner’s limits.
Planning to be away for 14 consecutive days or a total of 30 days in the next six months, which would prevent attending study visits or training sessions.
Having had or planning obesity surgery (except liposuction or tummy tuck performed more than a year ago).
Having had or planning endoscopic or device‑based obesity treatments (like gastric balloons or duodenal liners) within the past six months.
Having obesity caused by other hormonal disorders (such as Cushing syndrome) or known genetic forms of obesity (like MC4R deficiency or Prader‑Willi syndrome).
Being currently breastfeeding.
Having structural heart or blood‑vessel disease, such as coronary heart disease, heart failure, or a previous stroke.
Having atrial fibrillation, an irregular heart rhythm.

Where you can join this trial?

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Other Sites

Site Name	City	Country	Status
Klinikum der Technischen Universitaet Muenchen (TUM Klinikum)	Munich	Germany

Trial status

Country	Status	Recruitment Start
Germany	Not yet recruiting	30.06.2026

Trial locations

Investigated Drugs:

Tirzepatide

Mounjaro is a medication that contains tirzepatide, a drug that works on two hormones (GIP and GLP‑1) to help control blood sugar and promote weight loss. It is given as a subcutaneous injection using a pre‑filled pen. In this study, participants receive the medication while they follow either a resistance‑training program or usual care, so the drug’s role is to provide the standard medical treatment for obesity while the researchers look at how exercise may affect muscle changes.

Resistance training is a structured exercise program that focuses on strengthening the muscles, especially in the thighs. Participants perform specific weight‑lifting or body‑weight exercises under supervision, aiming to increase the size and function of the skeletal muscle. In the trial, this therapy is compared to usual care to see if it can help preserve or grow thigh muscle volume while participants are taking tirzepatide.

Investigated Diseases:

Obesity

Obesity – Obesity is a condition in which excess body fat accumulates to a level that may affect health. It usually develops gradually as a result of consuming more calories than are burned over time. As weight increases, the body stores more fat in the abdomen, thighs, and other areas. This excess fat can lead to the body working harder during everyday activities. Over months or years, the added weight can cause the muscles and joints to feel heavier and may reduce physical stamina. The condition tends to persist unless lifestyle changes are made.

Trial ID:

2026-526200-69-00

Protocol code:

RESIST-26-HAL-0150-I

Trial Phase:

Therapeutic confirmatory (Phase III)

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Resistance Training to Preserve Thigh Muscle Volume in Adults with Obesity Treated with Tirzepatide (Phase IV Randomized Trial)

What is this study about?

Who Can Join the Study?

Who Cannot Join the Study?