ObesityNCT03238794
Bariatric Surgery Versus Diet Alone in the Bile Acid Pathway and Weight Loss
A study testing Roux-En-Y Gastric Bypass and Low-calorie Diet in people with Obesity, run by Mayo Clinic at 1 site in United States.
Trial summary
It is unknown whether the bile acid pathway reacts differently to weight loss resulting from Roux-En-Y Gastric Bypass (RYGB) surgery than weight loss resulting from caloric restriction alone. Read more about this study
- Who is it for?
- Ages 18 to 65 years
- Conditions the study is for
- Obesity
- What is being tested?
- Roux-En-Y Gastric Bypass and Low-calorie Diet
- Type of treatment
- Surgery or procedure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 21 participants
- Where
- 1 siteUnited States
- Study dates
- 17 May 2019to 11 Jan 2027
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 65 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Women of childbearing potential will have negative pregnancy tests within 48 hours of enrolment.
- BMI: ≥ 40
- Individuals who have elected to have RYGB at the Mayo Clinic Bariatric Center of Excellence, and individuals with a BMI ≥40 who are otherwise healthy with controlled cardiac, pulmonary, gastrointestinal, hepatic, renal, hematological, neurological, or endocrine disorders. The RYGB participants will be invited to participate when their surgery is scheduled at the Mayo Clinic Bariatric Center of Excellence.
- The non-RYGB participants (BMI ≥40) will be otherwise healthy individuals with no unstable psychiatric disease and no unstable cardiac, pulmonary, gastrointestinal, hepatic, renal, hematological, neurological, or endocrine disorders.
Who cannot join
- History of abdominal surgery including cholecystectomy and other than appendectomy, Caesarian section or tubal ligation.
- Positive history of chronic gastrointestinal diseases, or systemic disease that could affect gastrointestinal motility, or use of medications that may alter gastrointestinal motility, appetite or absorption, e.g., orlistat, phentermine.
- Significant untreated psychiatric dysfunction based upon screening with the Hospital Anxiety and Depression Inventory (HAD), a self-administered alcoholism screening test (AUDIT-C) and the Questionnaire on Eating and Weight Patterns (binge eating disorders and bulimia). If such a dysfunction is identified by a depression or anxiety score >11 or difficulties with substance or eating disorders, the participant will be excluded and given a referral letter to his/her primary care doctor for further appraisal and follow-up. The AUDIT-C is a 3-item alcohol screening questionnaire that reliably identifies participants who are hazardous alcohol drinkers or have active alcohol use disorders. In men, a score of 4 or more is above the recommended limits will be reviewed by study personnel. In women, a score of 3 or more is above the recommended limits will be reviewed by study personnel. However when the points are above recommended limits, the provider will review the patient's alcohol intake over the past few months to confirm accuracy and determine study eligibility.
- Any acute or chronic condition or other disease that, in the opinion of the Investigator, would limit the subject's ability to complete and/or participate in this clinical study.Participant activities:
- If recruited for the investigation participants will be asked to refrain from donating blood; refrain from participating in other research studies; avoid taking any additional over the counter or prescription medications or herbal supplements that have not been reviewed and approved by the physician or the study coordinator until the study has been completed
Trial locations and contacts
1 site in 1 country.
United States1 site
Mayo Clinic in Rochester
Rochester, Minnesota, 55905
About this study
Official title: Effect of Weight Loss Through RYGB Versus Weight Loss Through Caloric Restriction on the Bile Acid Pathway
It is unknown whether the bile acid pathway reacts differently to weight loss resulting from Roux-En-Y Gastric Bypass (RYGB) surgery than weight loss resulting from caloric restriction alone.
Read the detailed description
Participants will be placed into two groups. The Roux-En-Y Gastric Bypass (RYGB) group will consist of participants who will have elected to have RYGB at the Mayo Clinic Bariatric Center of Excellence. The Diet group will have a low-calorie diet prescribed by a registered dietitian. Both groups will collect stool from every bowel movement 2 days before presenting for baseline testing. Both group participants will present for baseline testing after an overnight fast and before intervention (RYGB or low calorie diet). Participants will consume a standard breakfast provided by study staff and blood samples will be collected at -15, 0, 15, 30,45,60,90,120,150,180,210,240,300,360 minutes. Appetite and satiation ratings will be recorded via questionnaires during that day every 15 minutes for the first 90 minutes, then every 30 minutes. Participants will repeat this regimen again after losing 7% of their body weight after having RYGB or low calorie diet.
- Conditions
- Obesity
- Being tested
- Roux-En-Y Gastric Bypass, Low-calorie Diet
- Keywords
- Body Mass Index, gastric, bypass, bariatric surgery, bile acid, weight loss, diet, low calorie
- Medical subject headings
- Obesity, Weight Loss
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Roux-En-Y Gastric BypassProcedure or surgery
Also called RYGB
Food will be consumed as directed by their doctor as standard of care. A food log will be completed the week before visits 3 and 5.
Low-calorie DietOther
Food will be consumed as Week one will be liquid 400 to 500 kcal/day, weeks 2,3, and 4 will consist of 500-600 kcal/day of pureed food, weeks 5-8 will consist of 600-800 kcal/day of mechanical-soft food, weeks 9-12 will consist of 800 to 1000 kcal/day of soft foods, and the remainder of the study participants will be given 1000 to 1200 kcal/day of regular food.
| Study group | Role | What they receive |
|---|---|---|
| Roux-En-Y Gastric Bypass (RYGB) | Active comparator | Participants will have elected to have RYGB surgery per standard of care. Receives: Procedure: Roux-En-Y Gastric Bypass |
| Low-calorie Diet | Active comparator | Participants will have a low-calorie diet prescribed by a registered dietitian. Receives: Other: Low-calorie Diet |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in Bile Acid (BA) excretion
Total Fecal BA excretion change measured in mcmoles/48 hours
Measured: baseline, 12 weeks
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted3 Aug 2017
- Study start17 May 2019
- Primary completion11 Jan 2027 (estimated)
- Study completion11 Jan 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for ObesityStudies of the same condition, open and under way.
- More trials run by Mayo ClinicThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 21 participants (actual)
Sponsor and investigators
- Lead sponsor
- Mayo Clinic
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Andres J. Acosta, M.D., Ph.D., Mayo Clinic
- Investigators
- Andres J Acosta, MD, Principal investigator, Mayo Clinic
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03238794
- Sponsor's protocol ID
- 16-008664
- Other IDs
- K23DK114460
- Status last verified
- Feb 2026
- First submitted
- 1 Aug 2017
- Last updated
- 11 Feb 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 11 Feb 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effect of Weight Loss Through RYGB Versus Weight Loss Through Caloric Restriction on the Bile Acid Pathway
- ClinicalTrials.gov ID
- NCT03238794
- Acronym / sponsor ID
- 16-008664
- Conditions
- Obesity
- Keywords
- Body Mass Index, gastric, bypass, bariatric surgery, bile acid, weight loss, diet, low calorie
- Study type
- Interventional
- Recruitment status
- Active, not recruiting
- Enrolment
- 21 participants (actual)
- Lead sponsor
- Mayo ClinicUniversity, hospital or other
- Collaborators
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
- Study start
- 17 May 2019 (actual)
- Primary completion
- 11 Jan 2027 (estimated)
- Study completion
- 11 Jan 2027 (estimated)
- First posted
- 3 Aug 2017 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
It is unknown whether the bile acid pathway reacts differently to weight loss resulting from Roux-En-Y Gastric Bypass (RYGB) surgery than weight loss resulting from caloric restriction alone.
Detailed description
Participants will be placed into two groups. The Roux-En-Y Gastric Bypass (RYGB) group will consist of participants who will have elected to have RYGB at the Mayo Clinic Bariatric Center of Excellence. The Diet group will have a low-calorie diet prescribed by a registered dietitian. Both groups will collect stool from every bowel movement 2 days before presenting for baseline testing. Both group participants will present for baseline testing after an overnight fast and before intervention (RYGB or low calorie diet). Participants will consume a standard breakfast provided by study staff and blood samples will be collected at -15, 0, 15, 30,45,60,90,120,150,180,210,240,300,360 minutes. Appetite and satiation ratings will be recorded via questionnaires during that day every 15 minutes for the first 90 minutes, then every 30 minutes. Participants will repeat this regimen again after losing 7% of their body weight after having RYGB or low calorie diet.
Study design
- Primary purpose
- Basic science
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Roux-En-Y Gastric Bypass (RYGB) | Active comparator | Procedure: Roux-En-Y Gastric BypassParticipants will have elected to have RYGB surgery per standard of care. |
| Low-calorie Diet | Active comparator | Other: Low-calorie DietParticipants will have a low-calorie diet prescribed by a registered dietitian. |
Who may qualify
- Ages
- 18 to 65 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (4 listed)
- Women of childbearing potential will have negative pregnancy tests within 48 hours of enrolment.
- BMI: ≥ 40
- Individuals who have elected to have RYGB at the Mayo Clinic Bariatric Center of Excellence, and individuals with a BMI ≥40 who are otherwise healthy with controlled cardiac, pulmonary, gastrointestinal, hepatic, renal, hematological, neurological, or endocrine disorders. The RYGB participants will be invited to participate when their surgery is scheduled at the Mayo Clinic Bariatric Center of Excellence.
- The non-RYGB participants (BMI ≥40) will be otherwise healthy individuals with no unstable psychiatric disease and no unstable cardiac, pulmonary, gastrointestinal, hepatic, renal, hematological, neurological, or endocrine disorders.
Key exclusion criteria (5 listed)
- History of abdominal surgery including cholecystectomy and other than appendectomy, Caesarian section or tubal ligation.
- Positive history of chronic gastrointestinal diseases, or systemic disease that could affect gastrointestinal motility, or use of medications that may alter gastrointestinal motility, appetite or absorption, e.g., orlistat, phentermine.
- Significant untreated psychiatric dysfunction based upon screening with the Hospital Anxiety and Depression Inventory (HAD), a self-administered alcoholism screening test (AUDIT-C) and the Questionnaire on Eating and Weight Patterns (binge eating disorders and bulimia). If such a dysfunction is identified by a depression or anxiety score >11 or difficulties with substance or eating disorders, the participant will be excluded and given a referral letter to his/her primary care doctor for further appraisal and follow-up. The AUDIT-C is a 3-item alcohol screening questionnaire that reliably identifies participants who are hazardous alcohol drinkers or have active alcohol use disorders. In men, a score of 4 or more is above the recommended limits will be reviewed by study personnel. In women, a score of 3 or more is above the recommended limits will be reviewed by study personnel. However when the points are above recommended limits, the provider will review the patient's alcohol intake over the past few months to confirm accuracy and determine study eligibility.
- Any acute or chronic condition or other disease that, in the opinion of the Investigator, would limit the subject's ability to complete and/or participate in this clinical study.Participant activities:
- If recruited for the investigation participants will be asked to refrain from donating blood; refrain from participating in other research studies; avoid taking any additional over the counter or prescription medications or herbal supplements that have not been reviewed and approved by the physician or the study coordinator until the study has been completed
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Roux-En-Y Gastric BypassAlso: RYGBFood will be consumed as directed by their doctor as standard of care. A food log will be completed the week before visits 3 and 5. | Procedure or surgery | Roux-En-Y Gastric Bypass (RYGB) |
| Low-calorie DietFood will be consumed as Week one will be liquid 400 to 500 kcal/day, weeks 2,3, and 4 will consist of 500-600 kcal/day of pureed food, weeks 5-8 will consist of 600-800 kcal/day of mechanical-soft food, weeks 9-12 will consist of 800 to 1000 kcal/day of soft foods, and the remainder of the study participants will be given 1000 to 1200 kcal/day of regular food. | Other | Low-calorie Diet |
Primary outcome
Change in Bile Acid (BA) excretion
Time frame: baseline, 12 weeks
Total Fecal BA excretion change measured in mcmoles/48 hours
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 11 Feb 2026.
- Mayo Clinic Clinical TrialsLink provided by the sponsor.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Andres J Acosta, MD principal investigator
Mayo Clinic
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Roux-En-Y Gastric Bypass and Low-calorie Diet in people with Obesity, run by Mayo Clinic at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 5 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: under way, not looking for participants, as of the sponsor's last update on 11 Feb 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in Bile Acid (BA) excretion (time frame: baseline, 12 weeks). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 11 Feb 2026.