A gut-microbiota–friendly diet after bariatric surgery to help eating habits and taste

Is this trial a fit for you?

A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.

What this trial studies

Adults aged 25–65 undergoing sleeve gastrectomy or Roux-en-Y gastric bypass are assigned to receive either nutritional counseling that promotes gut microbiota diversity or standard nutritional counseling after surgery. The interventions focus on post-operative dietary guidance and follow participants for one year. Outcomes include measures of gut microbiota diversity, food preferences and eating behaviors, sensory profiles (taste and smell), fasting and postprandial gut and digestive hormones, cardiometabolic markers, mental health, and physical activity. The goal is to link dietary patterns that favor microbiota diversity with long-term weight maintenance and changes in sensory and metabolic function after bariatric procedures.

Why it matters

Who can join: the full rules

Inclusion Criteria:

* Between 25 and 65 years old
* Undergoing either sleeve gastrectomy or Roux-en-Y gastric bypass
* With grade 3 obesity (BMI≥40 kg/m²) or with BMI≥35 kg/m² and at least one comorbidity likely to be improved after surgery, with the exception of type 2 diabetes
* Signed consent form
* Living less than an hour and 30 minutes from the hospital
* Presence of effective and stable contraception for women of childbearing potential

Exclusion Criteria:

* Type 2 diabetes
* Presence of a contraindication to bariatric surgery
* Presence of gastrointestinal pathologies with an inflammatory component, known gastroparesis, total gastrectomy, colectomy, exocrine pancreatic insufficiency, known endocrine pathologies inducing hyperglycaemia (uncontrolled dysthyroidism, acromegaly, hypercorticism, etc.), severe chronic renal insufficiency (\< 30mL/min), or hepatocellular insufficiency
* Claustrophobic
* Pregnant or breastfeeding women
* Taking an obesity treatment 3 months before surgery
* Taking a corticoids, immunosuppression, anabolizing, or growing hormones, antibody treatments less than 3 months before inclusion
* Daily taking of laxatives or drugs that can strongly interfere with the composition of the intestinal microbiota. If taken sporadically, the patient can be included at a distance (3 weeks) from the laxatives taken.
* Specific diets (vegetarian, vegan or without gluten)
* No French speaker
* Already included in other study
* Donated blood in the last two months
* Without freezer access
* With allergy or intolerance to food propose in ad libitum buffet

Where it's running

• Hospital Edouard Herriot, digestive surgery department
  Lyon, France Recruiting
• Centre de recherche en nutrition humaine de Rhône-Alpes
  Pierre-Bénite, France Not yet recruiting
• Hôpital Lyon sud, Endocrinology Diabetes Nutrition department
  Pierre-Bénite, France Not yet recruiting

Study contacts

• Study coordinator: Julie-Anne NAZARE
• Email: julie-anne.nazare@univ-lyon1.fr
• Phone: +33 6 88 87 09 62

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How to take part

1. Review the eligibility criteria above with your treating physician.
2. Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
3. Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.