ObesityNCT06681246
The Role of Microbiome in Recurrent Obesity Before and After Antibiotic/Placebo Treatment
A study testing Antibiotic treatment in people with Obesity and Weight Loss, run by Weizmann Institute of Science at 1 site in Israel.
Trial summary
This past century witnessed a significant increase in the prevalence of obesity. Successful weight loss maintenance is defined as losing at least 10% of the initial body weight and maintaining it for at least one year. Read more about this study
- Who is it for?
- Ages 18 to 65 yearsHealthy volunteers can take part
- Conditions the study is for
- Obesity, Weight Loss
- What is being tested?
- Antibiotic treatment
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 200 participants
- Where
- 1 siteIsrael
- Study dates
- 11 Dec 2024to Dec 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
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- 28 < BMI< 40
- Age - 18-65
- Capable of working with a smartphone application
Who cannot join
- Consumption of antibiotics/probiotics/oral antifungals 2 months prior to the first day of the experiment.
- Pregnancy, fertility treatments, breastfeeding women six months prior to enrollment and during the study.
- Chronic disease, to the discretion of the study team (e.g. AIDS, Cushing syndrome, CKD, acromegaly etc.)
- Cancer and recent anticancer treatment
- Psychiatric disorders, to the discretion of the study team.
- Coagulation disorders
Show all 17Show fewer
- IBD (inflammatory bowel diseases)
- Bariatric surgery.
- Eating disorders (Anorexia nervosa. Bulimia nervosa. Binge eating disorder, Night eating syndrome).
- Alcohol or substance abuse
- Weight loss attempts 6 months prior to the first day of the experiment - using weight loss medication.
- Drastic changes in nutritional habits six months prior to the first day of the study - to the discretion of the study team.
- Allergy to penicillin.
- Life threatening reaction after consumption of cephalosporins.
- History of CDI
- Liver disease
- History of serious unresolved diarrhea in response to antibiotic treatment to the discretion of the study doctor.
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Israel1 site, 1 recruiting
- Recruiting
Weizmann Institute of Science
Rehovot
Barbara Raykhel
About this study
This past century witnessed a significant increase in the prevalence of obesity. Successful weight loss maintenance is defined as losing at least 10% of the initial body weight and maintaining it for at least one year. However, keeping a low body weight is rarely maintained, as 80% of people who lost 10% of their body weight will return to their initial weight within a year. Although there is no agreement as to what contributes to the recurrent weight regain phenomenon (also known as 'weight cycling' or 'yo-yo diet'), it is strongly associated with the risk of developing metabolic risk factors and their complications, including heart disease and all-cause mortality. Altering the gut microbiota is one method to treat disease states associated with gut bacteria. Antibiotics consumption is known to influence host glycemic response through changes induced in microbiome composition and function. Therefore, it may be a possible pathway to jumpstart changes in the gut microbiota.
This study will determine whether microbiome modulation might be a possible future target against recurrent obesity in humans and whether orally administered antibiotic treatment post-weight loss might be an effective intervention to prevent weight regain.
Read the detailed description
This is a placebo-controlled, double blinded interventional study evaluating the effect of antibiotic treatment in the prevention of weight regain after a successful weight loss intervention.
Volunteers will be recruited in the following ways: e-mail, and social media. Volunteers wishing to participate will be asked to complete a questionnaire regarding the aforementioned inclusion and exclusion criteria. Volunteers who qualify for the study will be invited to an introductory meeting at the Weizmann Institute of Science. The details of the experiment and potential risks or discomforts involved in it will be presented, after which the volunteers will sign an informed consent form. Volunteers will start the study and become active participants for a maximal duration of one year.
Samples collected for the study will be used for microbiota profiling (stool and oral), metabolomics (stool, blood) and for bomb calorimeter (stool).
The study will comprise of four parts:
- Baseline - one week of profiling and screening.
- Nutritional intervention - weight loss intervention which will be based on personalized hypocaloric diet restriction. Meetings will occur twice a month starting from the second week of the study for a three-month period.
- Antibiotic treatment - 10 days of either antibiotics- Augmentin (amoxicillin+clauvonate), 875mg, 2 /day, or 10 days of placebo pills, 2/day.
- Follow-up meetings - total follow up of 9 months after antibiotic/placebo treatment. Meetings will occur once a month for the first 3 months of the follow up period, and once every 3 months, afterwards.
- Conditions
- Obesity, Weight Loss
- Being tested
- Antibiotic treatment, Placebo
- 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.
Antibiotic treatmentOther
10 days of either antibiotics- Augmentin (amoxicillin+clauvonate), 875mg, 2 /day
PlaceboOther
consist of a combination of agarose in normal saline/glycerol
| Study group | Role | What they receive |
|---|---|---|
| Antibiotic treatment | Experimental | intervention arm Receives: Other: Antibiotic treatment |
| Placebo | Placebo comparator | placebo capsules administration Receives: Other: Placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
microbiome composition
using stool and oral samples
Measured: 1 year
weight
weight (kg)
Measured: 1 year
Secondary outcomes (1)
glycemic response
continues glucose monitor (CGM)
Measured: 1 year
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted8 Nov 2024
- Study start11 Dec 2024
- Primary completionDec 2026 (estimated)
- Study completionDec 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.
- 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
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind
- Who is masked
- Participant, Care provider, Investigator, Outcomes assessor
- Enrolment
- 200 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Weizmann Institute of Science
- Sponsor type
- University, hospital or other
- Collaborators
- Hadassah Medical Organization
- Responsible party
- Sponsor
- Investigators
- Hila Elinav, Doctor, Principal investigator, Hadassah Medical Organization
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06681246
- Sponsor's protocol ID
- 0744-21-HMO
- Status last verified
- Nov 2025
- First submitted
- 6 Nov 2024
- Last updated
- 11 Aug 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 11 Aug 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Role of Microbiome in Recurrent Obesity Before and After Antibiotic/Placebo Treatment
- ClinicalTrials.gov ID
- NCT06681246
- Acronym / sponsor ID
- 0744-21-HMO
- Conditions
- Obesity, Weight Loss
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 200 participants (estimated)
- Lead sponsor
- Weizmann Institute of ScienceUniversity, hospital or other
- Collaborators
- Hadassah Medical Organization
- Study start
- 11 Dec 2024 (actual)
- Primary completion
- Dec 2026 (estimated)
- Study completion
- Dec 2027 (estimated)
- First posted
- 8 Nov 2024 (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.
This past century witnessed a significant increase in the prevalence of obesity. Successful weight loss maintenance is defined as losing at least 10% of the initial body weight and maintaining it for at least one year. However, keeping a low body weight is rarely maintained, as 80% of people who lost 10% of their body weight will return to their initial weight within a year. Although there is no agreement as to what contributes to the recurrent weight regain phenomenon (also known as 'weight cycling' or 'yo-yo diet'), it is strongly associated with the risk of developing metabolic risk factors and their complications, including heart disease and all-cause mortality. Altering the gut microbiota is one method to treat disease states associated with gut bacteria. Antibiotics consumption is known to influence host glycemic response through changes induced in microbiome composition and function. Therefore, it may be a possible pathway to jumpstart changes in the gut microbiota.
This study will determine whether microbiome modulation might be a possible future target against recurrent obesity in humans and whether orally administered antibiotic treatment post-weight loss might be an effective intervention to prevent weight regain.
Detailed description
This is a placebo-controlled, double blinded interventional study evaluating the effect of antibiotic treatment in the prevention of weight regain after a successful weight loss intervention.
Volunteers will be recruited in the following ways: e-mail, and social media. Volunteers wishing to participate will be asked to complete a questionnaire regarding the aforementioned inclusion and exclusion criteria. Volunteers who qualify for the study will be invited to an introductory meeting at the Weizmann Institute of Science. The details of the experiment and potential risks or discomforts involved in it will be presented, after which the volunteers will sign an informed consent form. Volunteers will start the study and become active participants for a maximal duration of one year.
Samples collected for the study will be used for microbiota profiling (stool and oral), metabolomics (stool, blood) and for bomb calorimeter (stool).
The study will comprise of four parts:
- Baseline - one week of profiling and screening.
- Nutritional intervention - weight loss intervention which will be based on personalized hypocaloric diet restriction. Meetings will occur twice a month starting from the second week of the study for a three-month period.
- Antibiotic treatment - 10 days of either antibiotics- Augmentin (amoxicillin+clauvonate), 875mg, 2 /day, or 10 days of placebo pills, 2/day.
- Follow-up meetings - total follow up of 9 months after antibiotic/placebo treatment. Meetings will occur once a month for the first 3 months of the follow up period, and once every 3 months, afterwards.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Quadruple blind (participant, care provider, investigator, outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Antibiotic treatment | Experimental | Other: Antibiotic treatmentintervention arm |
| Placebo | Placebo comparator | Other: Placeboplacebo capsules administration |
Who may qualify
- Ages
- 18 to 65 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (3 listed)
- 28 < BMI< 40
- Age - 18-65
- Capable of working with a smartphone application
Key exclusion criteria (17 listed)
- Consumption of antibiotics/probiotics/oral antifungals 2 months prior to the first day of the experiment.
- Pregnancy, fertility treatments, breastfeeding women six months prior to enrollment and during the study.
- Chronic disease, to the discretion of the study team (e.g. AIDS, Cushing syndrome, CKD, acromegaly etc.)
- Cancer and recent anticancer treatment
- Psychiatric disorders, to the discretion of the study team.
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 |
|---|---|---|
| Antibiotic treatment10 days of either antibiotics- Augmentin (amoxicillin+clauvonate), 875mg, 2 /day | Other | Antibiotic treatment |
| Placeboconsist of a combination of agarose in normal saline/glycerol | Other | Placebo |
Primary outcome
microbiome composition
Time frame: 1 year
using stool and oral samples
weight
Time frame: 1 year
weight (kg)
1 secondary outcome
glycemic response
Time frame: 1 year
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 Aug 2026.
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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.
Hila Elinav, Doctor principal investigator
Hadassah Medical Organization
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Antibiotic treatment in people with Obesity and Weight Loss, run by Weizmann Institute of Science at 1 site in Israel.
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 3 inclusion and 17 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: looking for participants now, as of the sponsor's last update on 11 Aug 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 Israel. 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. Some participants in this study may receive a placebo. 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?
Contact Eran Elinav, Professor (+97289349174, Eran.Elinav@weizmann.ac.il), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
microbiome composition (time frame: 1 year). The study lists 2 primary outcomes in all. 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 Aug 2026.