Exploring how gut bacteria affect weight regain after losing weight

The Role of Microbiome in Recurrent Obesity Before and After Antibiotic/Placebo Treatment

NA · Weizmann Institute of Science · NCT06681246

This study tests whether taking antibiotics after losing weight can help people keep the weight off by looking at how gut bacteria play a role in weight maintenance.

Quick facts

PhaseNA
Study typeInterventional
Enrollment200 (estimated)
Ages18 Years to 65 Years
SexAll
SponsorWeizmann Institute of Science (other)
Locations1 site (Rehovot)
Trial IDNCT06681246 on ClinicalTrials.gov

What this trial studies

This interventional study investigates the impact of antibiotic treatment on preventing weight regain in individuals who have successfully lost weight. Participants will undergo a personalized hypocaloric diet followed by a 10-day course of either antibiotics or a placebo. The study includes microbiota profiling and metabolomics assessments to understand the relationship between gut bacteria and weight maintenance. Participants will be monitored for a total of one year, with follow-up meetings to assess outcomes.

Who should consider this trial

Good fit: Ideal candidates are adults aged 18-65 with a BMI between 28 and 35 who are capable of using a smartphone application.

Not a fit: Patients with chronic diseases, recent cancer treatment, or significant psychiatric disorders may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could provide a novel approach to help individuals maintain weight loss and reduce the risk of obesity-related health complications.

How similar studies have performed: While the role of the microbiome in obesity is being explored, this specific approach using antibiotics for weight maintenance is relatively novel and has not been extensively tested.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* 28\<BMI\<35
* Age - 18-65
* Capable of working with a smartphone application

Exclusion Criteria:

* 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
* 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.

Where this trial is running

Rehovot

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.

View on ClinicalTrials.gov →

Conditions: Obesity, Weight Loss

Last reviewed 2026-05-15 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.