Impact of a Pro-diversity Gut Microbiota Diet After a Bariatric Surgery on Gut Microbiota, Eating Behaviour and Sensory Function (BariaGut Taste)

Randomised Controlled Trial Evaluating the Impact of a Pro-diversity Gut Microbiota Diet on Gut Microbiota, Eating Behaviour and Sensory Function in Patients Who Have Undergone Bariatric Surgery

Bariatric surgery is the most effective treatment for long-term weight loss and reducing obesity-related health risks. It alters the gastrointestinal tract as well as metabolic and hormonal functions, influencing eating behaviour. However, weight loss outcomes and long-term maintenance vary between patients, likely due to changes in the gut microbiota. Dietary recommendations aimed at improving microbiota diversity could help support sustained weight loss after surgery.

The BariaGut Taste study aims to compare two dietary approaches following bariatric surgery: nutritional counselling promoting gut microbiota diversity versus standard nutritional counselling. One year after surgery, the study will evaluate differences in microbiota diversity, changes in food preferences and eating behaviours, sensory profiles (taste, smell), levels of digestive and gut hormones fasting, before and after eating, cardiometabolic parameters, mental health, physical activity, and more, to better understand Bariatric surgery is the most effective treatment for long-term weight loss and reducing obesity-related health risks. It alters the gastrointestinal tract as well as metabolic and hormonal functions, influencing eating behaviour. However, weight loss outcomes and long-term maintenance vary between patients, likely due to changes in the gut microbiota. Dietary recommendations aimed at improving microbiota diversity could help support sustained weight loss after surgery.

The BariaGut Taste study aims to compare two dietary approaches following bariatric surgery: nutritional counselling promoting gut microbiota diversity versus standard nutritional counselling. One year after surgery, the study will evaluate differences in microbiota diversity, changes in food preferences and eating behaviours, sensory profiles (taste, smell), levels of digestive and gut hormones fasting, before and after eating, cardiometabolic parameters, mental health, physical activity, and more, to better understand the mechanisms that may explain variations in response to bariatric surgery.

The BariaGut Taste study is a prospective, randomized, controlled trial with two parallel groups, involving non-diabetic patients aged 25 to 65 y undergoing either sleeve gastrectomy or Roux-en-Y gastric bypass. The trial will be conducted at the digestive surgery department of Edouard Herriot Hospital, the endocrinology-diabetes-nutrition department of Lyon Sud Hospital Center, and the Human Nutrition Research Center Rhône-Alpes. 60 participants are expected to be recruited, with 30 in each arm.

Participants will be enrolled before surgery during a routine care visit with the surgeon. They will then undergo a metabolic assessment visit conducted exclusively for research purposes. This visit will allow to collect baseline data on primary outcomes via blood, expired air, and stool samples, anthropometric measurements, indirect calorimetry, a battery of questionnaires (TFEQ-21, DEBQ, PHQ-9, SF36, GSES, PANAS, ESUL, BES, DERS, GAD-7, IPAQ, BAQ, GSRS, sensory alterations, Bristol and Likert scales, and FNS), computerized food preference tests (LFPQ), and a standardized, video-recorded ad libitum buffet.

Participants will be followed up at 3, 6, and 12 months after surgery through visits combining clinical care and research assessments. The dietary interventions specific to each group will be provided since the 3-month visit. The assessments conducted before surgery will be repeated at 6 and 12 months, also integrating clinical care objectives.

Additional blood, stool, and adipose tissue samples collected during surgery will be stored to create a biobank.

Study Overview

• Status: Recruiting
• Conditions: Bariatric Surgery; Obesity (Disorder)
• Intervention / Treatment: Other: Nutritional counseling

• Study Type: Interventional
• Enrollment (Estimated): 60
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Julie-Anne NAZARE; Phone Number: +33 6 88 87 09 62; Email: julie-anne.nazare@univ-lyon1.fr
• Study Contact Backup: Name: Berenice SEGRESTIN

Study Locations

• France
  • Lyon, France, 69310
    • Recruiting
    • Hospital Edouard Herriot, digestive surgery department
    • Contact: Maud ROBERT; Phone Number: +33 4 72 11 62 63; Email: maud.robert@chu-lyon.fr
  • Pierre-Bénite, France, 69310
    • Not yet recruiting
    • Centre de recherche en nutrition humaine de Rhône-Alpes
    • Contact: Julie-Anne NAZARE; Email: Julie-anne.nazare@univ-lyon1.fr
  • Pierre-Bénite, France, 69310
    • Not yet recruiting
    • Hôpital Lyon sud, Endocrinology Diabetes Nutrition department
    • Contact: Berenice SEGRESTIN; Phone Number: +33 4 78 86 44 48; Email: berenice.segrestin@chu-lyon.fr

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

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

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Participants with nutritional counselling promoting gut microbiota diversity; Given the low amounts of food consumed during the first months after surgery, the specific nutritional recommendations for this group will be implemented starting 3 months post-surgery. Before 3 months, participants will receive the standard nutritional recommendations of routine care after bariatric surgery, identical to those given to the second group (see below). From 3 months onwards, participants will be encouraged to increase the consumption of certain specific foods known for their benefits on the gut microbiota, particularly for promoting gut bacterial diversity, in addition to maintaining protein intake and paying attention to food textures. Summary sheets will be provided to help recall the recommendations.	Other: Nutritional counseling; Nutritional counseling
No Intervention: Participants with standard nutritional counselling; The nutritional recommendations given to participants in this group are those applied in routine care within the Endocrinology, Diabetes, and Nutrition (EDN) Department for patients who have undergone sleeve gastrectomy or gastric bypass (Roux-en-Y). These recommendations aim to maintain adequate protein intake and are adapted to the recent changes in their digestive tract (pureed then mashed food during the first postoperative month). During the first 6 months, patients' food intake is significantly below their nutritional needs. So it is important to pay close attention to hydration (away from meals) and macronutrient intake, especially proteins, as well as the progression of food texture and chewing.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Microbiota diversity 12 months after surgery	The change in the diversity of the microbiota (shot gun metagenomic analysis, counting the number of microbial genes), between before surgery and one year after surgery (delta) between the two dietary intervention groups.	Primary outcome will be assessed three times : before the surgery, 6 and 12 months after

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Eating behaviour during a standardised, filmed and validated ad libitum buffet : Food intake	energy intake, macro- and micronutrient intake The items chosen during the buffet from the 17 items that will be offered will be noted. The quantities in g and calories consumed of each item will be estimated from the weighing of the plates before and after the buffet, the contribution of each of the items to the energy intake will also be evaluated.	Before the surgery and at 6 and 12 month after
Eating behaviour during a standardised, filmed and validated ad libitum buffet: Nutritional quality	Nutritional quality through analysis of the foods chosen and consumed Buffet items are classified (pre-defined classification) into seven groups based on their macronutrient content and energy density: starchy foods, meat and fish, fruits and vegetables, dairy products, sweet desserts, sauces, and sweetened beverages. They are also classified according to their fat, sugar, and protein content, and their energy density (4 groups). The quantities consumed in grams and as a percentage of energy intake per group will be assessed for each subject and per visit.	Before the surgery and at 6 and 12 month after
Eating behaviour during a standardised, filmed and validated ad libitum buffet: Meal microstructure	time spent selecting food at the buffet, duration of ingestion, ingestion speed, total meal duration, number of bites per minute, total number of bites and bites by food type, and food choices Several indicators will be assessed for the buffet's microstructure based on the analysis of videos taken during the buffet: - Buffet time	Before the surgery and at 6 and 12 month after
Eating behaviour during a standardised, filmed and validated ad libitum buffet: Meal appreciation	time spent selecting food at the buffet, duration of ingestion, ingestion speed, total meal duration, number of bites per minute, total number of bites and bites by food type, and food choices Assessed with visual analog scale from 1(worse outcome) to 10 (better outcome)	Before the surgery and at 6 and 12 month after
Eating behaviour and preferences : Behaviors	binge eating using sub-scores from tthe BES (Binge Eating Scale) for binge eating BES : Binge Eating Scale - score from 0 to 46, score of 46 = highest level of binge eating disorder	Before the surgery and at 6 and 12 month after
Eating behaviour and preferences : Food preferences	Food preferences using the short version of the LFPQ (Leeds Food Preference Questionnaire) LFPQ : Leeds Food and Preference Questionnaire- score from 0 to 100 on preference or motivation for a type of food, high score = strong preference or motivation	Before the surgery and at 6 and 12 month after
Appetite : hunger level	Assessed using visual analog scales rated from 0 (worse outcome) to 10 (better outcome) on the following dimensions : hunger	Before the surgery and at 6 and 12 month after
Appetite : satiety	Assessed using visual analog scales rated rom 0 (worse outcome) to 10 (better outcome) on the following dimensions : feeling of satiety	Before the surgery and at 6 and 12 month after
Appetite : desire to eat	Assessed using visual analog scales rated from 0 (worse outcome) to 10 (better outcome) on the following dimensions : desire to eat	Before the surgery and at 6 and 12 month after
Appetite : prospective consumption	Assessed using visual analog scales rated from 0 (worse outcome) to 10 (better outcome) on the following dimensions : consommation	Before the surgery and at 6 and 12 month after
Appetite : meal appreciation	Assessed using visual analog scales rated rom 0 (worse outcome) to 10 (better outcome) on the following dimensions : meal appreciation	Before the surgery and at 6 and 12 month after
Sensory functions : detection scores	Assessed using Taste Strips tests	Before the surgery and at 6 and 12 month after
Sensory functions : intensity	Assessed using Taste Strips tests	Before the surgery and at 6 and 12 month after
Sensory functions : pleasantness	Assessed using Taste Strips tests	Before the surgery and at 6 and 12 month after
Sensory functions : edibility of tastes	Assessed using Taste Strips tests	Before the surgery and at 6 and 12 month after
Sensory functions : edibility of odors	Assessed using Taste Strips tests	Before the surgery and at 6 and 12 month after
Self-reported alterations in sensory functions	Assessed using dedicated questions	Before the surgery and at 6 and 12 month after
Body perception	Assessed using the BAQ questionnaire (Body Awareness Questionnaire) BAQ : Body Awarness Questionnaire - score from 13 to 65, score of 65 = positive assessment of one's body	Before the surgery and at 6 and 12 month after
Appetite : desire to eat	Assessed using visual analog scales rated from 0 to 10 on the following dimensions: desire to eat	Before the surgery and at 6 and 12 month after
Appetite : prospective consumption	Assessed using visual analog scales rated from 0 to 10 on the following dimensions	Before the surgery and at 6 and 12 month after
Microbiota composition	Evaluated via gene function analysis from metagenomics data, metabolomics and short-chain fatty acid quantification	Before the surgery and at 6 and 12 month after
Microbiota function	Evaluated via gene function analysis from metagenomics data, metabolomics and short-chain fatty acid quantification	Before the surgery and at 6 and 12 month after
Endocrine, digestive or intestinal hormones	Blood sample to measure : Adiponectin µg/ml	Before the surgery and at 6 and 12 month after Fasting (all except acylated ghrelin), before the buffet and 1 hour after (adiponectin, total GLP1, ghrelin, acylated ghrelin, total PYY, glucagon, GIP and FGF-19)
Exhaled gas profiles	Assessed by volatolomic signatures	Before the surgery and at 6 and 12 month after
Cardio-metabolic profile parameters	BMI will be assessed	Before the surgery and at 6 and 12 month after
Cardio-metabolic profile parameters	Energy metabolism by indirect calorimetry	Before the surgery and at 6 and 12 month after
Cardio-metabolic profile parameters	postprandial plasma markers: We will assess: glycaemia (g/L)	Before the surgery and at 6 and 12 month after
Cardio-metabolic profile parameters	CRP	Before the surgery and at 6 and 12 month after
Vital parameters	Blood pressure	Before the surgery and at 6 and 12 month after
Nutritional status: Blood vitamin	Blood vitamin status : For the research, we will focus only whether or not the participant has a deficiency in one of the vitamins measured (yes/no variable). The vitamins assessed are : - Vitamin B12 (pmol/L) should be above 145 pmol/L	Before the surgery and at 6 (except plasma fatty acid profile) and 12 month after
Nutritional status : Blood mineral	Blood mineral status: Calcium (mmol/L) should be above 64 mmol/L; Phosphor (mmol/L) should be above 0.81 mmol/L; Magnesium (mmol/L) should be above 0.66 mmol/L; Sodium (mmol/L) should be above 136 mmol/L; Potassium (mmol/L) should be above 3.4 mmol/L; Chlore (mmol/L) should be above 98 mmol/L	Before the surgery and at 6 (except plasma fatty acid profile) and 12 month after
Nutritional status : Plasma fatty acid	Plasma fatty acid profile	Before the surgery and at 6 (except plasma fatty acid profile) and 12 month after
Nutritional status : Protein	Protein status	Before the surgery and at 6 (except plasma fatty acid profile) and 12 month after
Average energy	Assessed using 3-day dietary recall randomly selected from the 7 days preceding the visits	Before the surgery and at 6 and 12 month after
macronutrients intakes and proportions	Assessed using 3-day dietary recall randomly selected from the 7 days preceding the visits	Before the surgery and at 6 and 12 month after
micronutrients intakes and proportions	Assessed using 3-day dietary recall randomly selected from the 7 days preceding the visits	Before the surgery and at 6 and 12 month after
Mental health: Quality of life	Quality of life using the SF36 questionnaire SF36 - health status questionnaire - score from 0 to 100, score of 100 = excellent perceived health	Before the surgery and at 6 and 12 month after
Mental health: Self-confidence	Self-confidence and self-efficacy using the GSES GSES: Generalized Self-Efficacy Scale - score of 10 to 40, score of 40 = strong confidence in one's ability to effectively manage different life situations and challenges	Before the surgery and at 6 and 12 month after
Mental health: Depression	Depression with PHQ-9 PHQ-9: Patient Health Questionnaire -score from 0 to 27, score of 27=severe depression	Before the surgery and at 6 and 12 month after
Mental health: Anxiety	Anxiety assessment using GAD-7 GAD-7: Generalized Anxiety Disorder - if score >7 then anxiety disorders should be suspected	Before the surgery and at 6 and 12 month after
Physical activity	Assessed using the short version of the IPAQ IPAQ: International Physical Activity Questionnaire - continuous daily energy expenditure score, high score means high AP The questionnaire allows the subject to be classified according to 3 levels of activity: inactive, moderate, high.	Before the surgery and at 6 and 12 month after
Emotions: positive and negative	positive and negative emotion assessed using the PANAS scale PANAS: Positive Affectivity and Negative Affectivity Scale - 2 scores from 10 to 50 - positive affectivity score = 50 best, negative affectivity score = 50 worst	Before the surgery and at 6 and 12 month after
Emotions: food phobias	food phobias using the FNS questionnaire FNS : Food Neophobia Scale -score from 10 to 70 - score of 70 = neophobia, i.e. less willingness to try new foods	Before the surgery and at 6 and 12 month after
Emotions: loneliness	loneliness using the ESUL questionnaire University of Laval Loneliness Scale - score from 20 to 80, score of 80 = most pronounced feeling of loneliness	Before the surgery and at 6 and 12 month after
Changes in stool consistency	Assessed using Bristol stool scale Bristol scale : 7 types of stools to choose from photo: type 1 = hard and lumpy stools, type 7 = completely liquid stools	Before the surgery and at 6 and 12 month after
Changes in stool frequency	Assessed using Bristol stool scale : 7 types of stools to choose from photo: type 1 = hard and lumpy stools, type 7 = completely liquid stools	Before the surgery and at 6 and 12 month after
Changes in gastrointestinal symptoms	Assessed using Bristol stool scale	Before the surgery and at 6 and 12 month after
Grade of hepatic steatosis	Evaluation by FibroScan® but only for patients who had a FibroScan® performed before surgery.	Before the surgery and at 12 month after
Grade of hepatic fibrosis	Evaluation by FibroScan® but only for patients who had a FibroScan® performed before surgery.	Before the surgery and at 12 month after
Eating behaviour and preferences : Behaviors	Behaviors (emotional eating and cognitive restraint) using score from the DEBQ (Dutch Eating Behavior Questionnaire) a DEBQ : Dutch Eating Behaviour Questionnaire : 3 sub-scores: cognitive restriction, reactivity to external stimuli and emotionality from 1 to 5, score 5 = strong impact of eating behavior	Before the surgery and at 6 and 12 month after
Hepatic metabolic flexibility	Assessed via the degree of alteration of MAMs (Mitochondia-Associated Membranes) in peripheral blood mononuclear cells (PBMCs), only for patients who had a FibroScan® performed before surgery.	Before the surgery and at 6 and 12 month after
Safety parameters	thyroid function: Thyroid function is assessed based on TSH levels in mIU/L (should be above 0.4 mIU/L and below 4.8 mIU/L), 2. The assessment for the research is whether the measures are within the limits or not (yes/no variable).	Before the surgery and at 6 and 12 month after
Compliance and follow-up of advice given during the intervention	Based on the three 24-hour reminders completed by participants before each visit, the dietitian will classify participants into three categories: good, average or poor compliance.	until month 12
Eating behaviour during a standardised, filmed and validated ad libitum buffet: Meal microstructure	time spent selecting food at the buffet	Before the surgery and at 6 and 12 month after
Eating behaviour during a standardised, filmed and validated ad libitum buffet: Meal microstructure	duration of ingestion	Before the surgery and at 6 and 12 month after
Eating behaviour during a standardised, filmed and validated ad libitum buffet: Meal microstructure	ingestion speed	Before the surgery and at 6 and 12 month after
Changes in stool consistency	Assessed using Likert scale Likert scale : 7 types of stools to choose from photo: type 1 = hard and lumpy stools, type 7 = completely liquid stools	Before the surgery and at 6 and 12 month after
Changes in stool consistency	Assessed using gastrointestinal symptoms using GSRS Gastrointestinal Symptom Questionnaire - score 15 to 105, score 105=severe gastrointestinal symptoms	Before the surgery and at 6 and 12 month after
Safety parameters	complete blood count	Before the surgery and at 6 and 12 month after
Safety parameters	AST	Before the surgery and at 6 and 12 month after
Safety parameters	ALT	Before the surgery and at 6 and 12 month after
Safety parameters	gamma GT	Before the surgery and at 6 and 12 month after
Safety parameters	bilirubin	Before the surgery and at 6 and 12 month after
Safety parameters	alkaline phosphate	Before the surgery and at 6 and 12 month after
Safety parameters	creatinine	Before the surgery and at 6 and 12 month after
Safety parameters	uric acid	Before the surgery and at 6 and 12 month after
Safety parameters	ionogram results: Sodium (mmol/L) which should be between 136 and 145 Potassium (mmol/L) which should be between 3.4 and 4.5 Chlorine (mmol/L) which should be between 98 and 107 Bicarbonates (mmol/L) which should be between 22 and 29	Before the surgery and at 6 and 12 month after
Safety parameters	coagulation : prothrombin time	Before the surgery and at 6 and 12 month after
Changes in stool frequency	Assessed using Likert scale	Before the surgery and at 6 and 12 month after
Changes in stool frequency	Assessed using gastrointestinal symptoms using GSRS : 15 questions with answers from No discomfort at all at Very severe discomfort (7 levels)	Before the surgery and at 6 and 12 month after
Changes in gastrointestinal symptoms	Assessed using Likert scale	Before the surgery and at 6 and 12 month after
Changes in gastrointestinal symptoms	gastrointestinal symptoms using GSRS	Before the surgery and at 6 and 12 month after
Eating behaviour during a standardised, filmed and validated ad libitum buffet: Meal microstructure	total meal duration	Before the surgery and at 6 and 12 month after
Eating behaviour during a standardised, filmed and validated ad libitum buffet: Meal microstructure	number of bites per minute	Before the surgery and at 6 and 12 month after
Eating behaviour during a standardised, filmed and validated ad libitum buffet: Meal microstructure	total number of bites	Before the surgery and at 6 and 12 month after
Eating behaviour during a standardised, filmed and validated ad libitum buffet: Meal microstructure	bites by food type	Before the surgery and at 6 and 12 month after
Eating behaviour during a standardised, filmed and validated ad libitum buffet: Meal microstructure	food choices	Before the surgery and at 6 and 12 month after
Eating behaviour during a standardised, filmed and validated ad libitum buffet: Meal microstructure	Calorie intake consumed per minute of the buffet	Before the surgery and at 6 and 12 month after
Safety parameters	ionogram results: Anion gap = (Na+ + K+) - (HCO3- + Cl-) (mmol/L) which should be between 12 and 20	Before the surgery and at 6 and 12 month after
Endocrine, digestive or intestinal hormones	Blood sample to measure : Ghrelin pg/ml acylated ghrelin pg/ml	Before the surgery and at 6 and 12 month after Fasting (all except acylated ghrelin), before the buffet and 1 hour after (adiponectin, total GLP1, ghrelin, acylated ghrelin, total PYY, glucagon, GIP and FGF-19)
Endocrine, digestive or intestinal hormones	Blood sample to measure : GIP pmol/l total GLP-1 : pmol/L glucagon : pmol/L	Before the surgery and at 6 and 12 month after Fasting (all except acylated ghrelin), before the buffet and 1 hour after (adiponectin, total GLP1, ghrelin, acylated ghrelin, total PYY, glucagon, GIP and FGF-19)
Endocrine, digestive or intestinal hormones	Blood sample to measure : total PYY : ng/L	Before the surgery and at 6 and 12 month after Fasting (all except acylated ghrelin), before the buffet and 1 hour after (adiponectin, total GLP1, ghrelin, acylated ghrelin, total PYY, glucagon, GIP and FGF-19)
Endocrine, digestive or intestinal hormones	Blood sample to measure : leptin : ng/ml	Before the surgery and at 6 and 12 month after Fasting (all except acylated ghrelin), before the buffet and 1 hour after (adiponectin, total GLP1, ghrelin, acylated ghrelin, total PYY, glucagon, GIP and FGF-19)
Cardio-metabolic profile parameters	We will assess: insulin (mU/L)	Before the surgery and at 6 and 12 month after
Cardio-metabolic profile parameters	We will assess: triglycerides (mmol/L), HDL (mmol/L), LDL (mmol/L), ApoB (mmol/L), sphingolipid (mmol/L) and unesterified fatty acid(mmol/L)	Before the surgery and at 6 and 12 month after
Cardio-metabolic profile parameters	we will calculate: HOMA-IR (=insulin*glycarmia/22.5) and the total cholesterol/HDL cholesterol ratio.	Before the surgery and at 6 and 12 month after
Cardio-metabolic profile parameters	postprandial plasma markers: We will assess: insulin (mU/L)	Before the surgery and at 6 and 12 month after
Nutritional status: Blood vitamin	Blood vitamin status : For the research, we will focus only whether or not the participant has a deficiency in one of the vitamins measured (yes/no variable). The vitamins assessed are : - Vitamin B9 (mmol/L) should be above 10.4 mmol/L	Before the surgery and at 6 (except plasma fatty acid profile) and 12 month after
Nutritional status: Blood vitamin	Blood vitamin status : For the research, we will focus only whether or not the participant has a deficiency in one of the vitamins measured (yes/no variable). The vitamins assessed are : - Vitamin B1 (nmol/L) should be above 78 nmol/L	Before the surgery and at 6 (except plasma fatty acid profile) and 12 month after
Nutritional status: Blood vitamin	Blood vitamin status : For the research, we will focus only whether or not the participant has a deficiency in one of the vitamins measured (yes/no variable). The vitamins assessed are : Vitamin C (µmol/L) should be above 25 µmol/L; Vitamin A (µmol/L) should be above 1.40 µmol/L	Before the surgery and at 6 (except plasma fatty acid profile) and 12 month after
Nutritional status : Blood mineral	Blood mineral status: Iron (µmol/L) should be above 5.8µmol/L; Selenium (µmol/L) should be above 56µmol/L; Zinc (µmol/L) should be above 9.20µmol/L	Before the surgery and at 6 (except plasma fatty acid profile) and 12 month after
Safety parameters	thyroid function: Thyroid function is assessed based on free thyroxine in pmol/L (should be above 11.9 pmol/L and below 21.9 pmol/L) The assessment for the research is whether the measures are within the limits or not (yes/no variable).	Before the surgery and at 6 and 12 month after
Safety parameters	thyroid function: Thyroid function is assessed based on free triiodothyronine in pmol/L (should be above 3.1 pmol/L and below 6.8 pmol/L). The assessment for the research is whether the three measures are within the limits or not (yes/no variable).	Before the surgery and at 6 and 12 month after
Cardio-metabolic profile parameters	Waist-to-hip ratio will be assessed	Before the surgery and at 6 and 12 month after
Vital parameters	resting heart rate	Before the surgery and at 6 and 12 month after
Safety parameters	coagulation : activated partial thromboplastin time	Before the surgery and at 6 and 12 month after
Safety parameters	coagulation : fibrinogen	Before the surgery and at 6 and 12 month after
Cardio-metabolic profile parameters	We will assess: total cholesterol (g/L)	Before the surgery and at 6 and 12 month after
Cardio-metabolic profile parameters	We will assess: HbA1c (mmol/mol),	Before the surgery and at 6 and 12 month after

Collaborators and Investigators

• Sponsor: Hospices Civils de Lyon

Study record dates

Study Major Dates

• Study Start (Actual): November 5, 2025
• Primary Completion (Estimated): November 5, 2027
• Study Completion (Estimated): April 5, 2029

Study Registration Dates

• First Submitted: August 14, 2025
• First Submitted That Met QC Criteria: November 25, 2025
• First Posted (Actual): December 5, 2025

Study Record Updates

• Last Update Posted (Actual): April 3, 2026
• Last Update Submitted That Met QC Criteria: April 2, 2026
• Last Verified: April 1, 2026

More Information

Terms related to this study

• Keywords: Bariatric surgery; gut microbiota; weight loss maintenance; food preferences; sensory alteration
• Additional Relevant MeSH Terms: Nutrition Disorders; Overnutrition; Body Weight; Overweight; Pathological Conditions, Signs and Symptoms; Behavior; Nutritional and Metabolic Diseases; Signs and Symptoms; Feeding Behavior; Obesity; Food Preferences; Health Care Quality, Access, and Evaluation; Investigative Techniques; Epidemiologic Methods; Data Collection; Health Care Evaluation Mechanisms; Quality of Health Care; Public Health; Environment and Public Health; Epidemiologic Measurements; Nutrition Assessment
• Other Study ID Numbers: 69HCL24_0033

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No