Investigating protein needs after gastric bypass surgery

Maintenance-phase PROtein Requirements After RouX-en-Y-gastric Bypass Surgery

Observational Universitaire Ziekenhuizen KU Leuven · NCT06853652

This study tests how much protein adult men need after having gastric bypass surgery to see if their needs are different from those of the general population.

Quick facts

Study typeObservational
Enrollment20 (estimated)
Ages18 Years to 65 Years
SexMale
SponsorUniversitaire Ziekenhuizen KU Leuven Academic / other
Locations1 site (Leuven)
Trial IDNCT06853652 on ClinicalTrials.gov

What this trial studies

This study examines the protein requirements of adult males who have undergone Roux-en-Y gastric bypass surgery at least one year prior. Using the Indicator Amino Acid Oxidation (IAAO) method, the research aims to determine if these protein needs are higher compared to those of the general population. Participants will undergo a series of tests to measure protein oxidation at varying intake levels, allowing researchers to calculate the average protein requirements for this specific group. The findings could provide valuable insights into dietary recommendations for post-bariatric surgery patients.

Who should consider this trial

Good fit: Ideal candidates are adult males aged 18 to 65 who have had Roux-en-Y gastric bypass surgery between one to ten years ago and have maintained stable weight.

Not a fit: Patients with active cancer, significant weight regain, or chronic diseases affecting amino acid metabolism may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could lead to improved dietary guidelines for protein intake in men after gastric bypass surgery.

How similar studies have performed: While there is limited data on this specific approach, studies on protein requirements post-bariatric surgery have shown varying results, indicating a need for further investigation.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

1. Male aged 18 - 65 years,
2. Primary RYGB surgery one to ten years before,
3. Weight stable within 5% over the last 3 months,
4. Normotensive or blood pressure controlled with antihypertensive therapy,
5. Provision of informed consent to participate,

Exclusion Criteria:

1. Current diagnosis of cancer or active cancer in the preceding 1 year,
2. Any chronic or acute disease which is known to affect amino acid absorption, metabolism, or requirements,
3. Weight loss after bariatric surgery of less than 40% of excess weight,
4. Weight regain after bariatric surgery greater than 20% of nadir weight,
5. Diabetes mellitus defined as a fasting plasma glucose concentration ≥ 7.0 mmol, or HbA1c less than 6.5%, or medical treatment for diabetes.

Where this trial is running

Leuven

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 Obesity and OverweightBariatric SurgeryProtein Requirement
Last reviewed 2026-06-13 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.