What affects muscle and fat changes after weight-loss surgery

PILOT STUDY: The Metabolic and Genetic Drivers of Body Composition Changes Following Weight Loss Surgery

Observational The University of Texas Medical Branch, Galveston · NCT07178704

We will follow people having bariatric surgery to see if differences in behavior, metabolism, or genes explain who loses muscle or regains weight after surgery.

Quick facts

Study typeObservational
Enrollment110 (estimated)
Ages18 Years to 65 Years
SexAll
SponsorThe University of Texas Medical Branch, Galveston Academic / other
Locations1 site (Galveston, Texas)
Trial IDNCT07178704 on ClinicalTrials.gov

What this trial studies

This prospective observational project will follow bariatric surgery patients before and for one year after surgery, collecting data on diet, hand-grip strength, and body composition changes (fat and muscle). A group of healthy control volunteers will be recruited for comparison, and a subset of gastric bypass patients aged 30–50 will be invited for detailed metabolic testing of nutrient use. Genetic analyses and behavioral surveys will be combined with metabolic and strength measures to identify factors linked to poor muscle preservation or weight regain. All procedures are conducted at The University of Texas Medical Branch in Galveston and no interventional treatments are administered as part of the protocol.

Who should consider this trial

Good fit: Ideal candidates are English-speaking adults scheduled for bariatric surgery at UTMB (ages 18–65, BMI 35–50), with a subset of gastric bypass patients aged 30–50 eligible for enhanced metabolic testing and healthy controls aged 30–50 with BMI 20–25 serving as comparisons.

Not a fit: Patients not having surgery at UTMB, those outside the specified age or BMI ranges, or those unable to complete follow-up visits or English consent procedures are unlikely to benefit from participation.

Why it matters

Potential benefit: If successful, findings could guide personalized perioperative care to protect muscle mass and reduce weight regain after bariatric surgery.

How similar studies have performed: Previous research has repeatedly shown bariatric surgery reduces body weight and can cause muscle loss, but applying combined metabolic and genetic profiling to predict individual muscle loss and weight regain is relatively new and not yet well established.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria (Healthy Volunteers):

* Age: 30 to 50 years at time of consent
* BMI: 20-25 kg.m-2
* Male or Female
* All races and ethnic backgrounds
* Ability to speak and read English
* Subject has provided informed consent in a manner approved by the IRB and is willing and able to comply with the trial procedures.

Inclusion Criteria (Bariatric Surgery Patients):

* Age: 18 to 65 years at time of consent
* BMI: 35-50 kg.m-2
* Scheduled to undergo bariatric surgery at UTMB
* All races and ethnic backgrounds
* Ability to speak and read English
* Subject has provided informed consent in a manner approved by the IRB and is willing and able to comply with the trial procedures.

Additional inclusion criteria for patients undergoing enhanced metabolic assessment:

* Age: restricted to 30 to 50 years of age
* Undergoing gastric bypass surgery

Exclusion Criteria (Healthy Volunteers):

* Heart, vascular, or pulmonary disease
* Uncontrolled blood pressure (systolic BP \> 170, diastolic BP \> 95 mmHg)
* Impaired renal function (creatinine \> 1.5 mg/dl)
* Anemia (hematocrit \< 33 % or donated blood in the past 12 weeks.)
* Diabetes mellitus or other untreated endocrine or metabolic disorder
* Recent (5 years or less) history of cancer
* Systemic steroids, anabolic steroids, growth hormone, or immunosuppressant use within 6 months.
* Recent (6 months) adherence to a weight-loss or weight-gain diet, resulting in a weight change of 10% or more.
* Body mass index \> 25.5 kg.m-2
* Body mass index \< 19.5 kg.m-2 or recent history (\< 12 months) of disordered eating.
* Acute infectious disease or chronic infection.
* Pregnancy or breast-feeding.
* Recent (1 month) consumption of protein-based sports supplements.
* Any medical condition that, in the opinion of the investigator, would place the subject at increased risk for participation.
* Known allergic reaction to any agent under investigation or required by the protocol, including Phenylketonuria.
* Unable to lie still in a supine position for 10 minutes.
* History of prior non-compliance or the presence or history of a psychiatric condition (including drug or alcohol addiction) that would, in the opinion of the investigator, make it difficult for the subject to comply with the study procedures or follow the investigators instructions.
* Concurrent participation in another research study.
* Use of an investigational agent in the 30 days prior to signing informed consent.

Exclusion Criteria (Bariatric Surgery Patients):

* Fails the medical criteria for bariatric surgery.
* Anemia (hematocrit \< 33 % or donated blood in the past 12 weeks.)
* Recent (5 years or less) history of cancer
* Systemic steroids, anabolic steroids, growth hormone, or immunosuppressant use within 6 months.
* Body mass index \< 35 or \> 50 kg.m-2.
* Acute infectious disease or chronic infection.
* Pregnancy or breast-feeding.
* Any medical condition that, in the opinion of the investigator, would place the subject at increased risk for participation.
* History of prior non-compliance that would, in the opinion of the investigator, make it difficult for the subject to comply with the study procedures or follow the investigator's instructions.
* Concurrent participation in another research study.
* Use of an investigational agent in the 30 days prior to signing informed consent.

Additional exclusion criteria for patients undergoing enhanced metabolic assessment:

* Known allergic reaction to any agent under investigation or required by the protocol, including Phenylketonuria.
* Unable to lie still in a supine position for 10 minutes.
* Previous bariatric surgery or undergoing a procedure other than gastric bypass (e.g. sleeve gastrectomy).

Where this trial is running

Galveston, Texas

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Bariatric Surgery PatientsBody compositionSarcopeniaWeight loss surgeryMuscle functionProtein metabolism
Last reviewed 2026-06-09 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.