Obesity (Disorder)BariaGut TasteNCT07268508
Impact of a Pro-diversity Gut Microbiota Diet After a Bariatric Surgery on Gut Microbiota, Eating Behaviour and Sensory Function
A study testing Nutritional counseling in people with Obesity (Disorder) and Bariatric Surgery, run by Hospices Civils de Lyon at 3 sites in France.
Trial summary
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. Read more about this study
- Who is it for?
- Ages 25 to 65 years
- Conditions the study is for
- Obesity (Disorder), Bariatric Surgery
- What is being tested?
- Nutritional counseling
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 60 participants
- Where
- 3 sitesFrance
- Study dates
- 5 Nov 2025to 5 Apr 2029
- 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 25 to 65 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- 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
Who cannot join
- 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
Show all 14Show fewer
- 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
Trial locations and contacts
3 sites in 1 country. Contact the study team or a site near you to ask about taking part.
Berenice SEGRESTIN contact
France3 sites, 3 recruiting
- Recruiting
Hospital Edouard Herriot, digestive surgery department
Lyon, 69310
Maud ROBERT, +33 4 72 11 62 63, maud.robert@chu-lyon.fr
- Not yet recruiting
Centre de recherche en nutrition humaine de Rhône-Alpes
Pierre-Bénite, 69310
Julie-Anne NAZARE, Julie-anne.nazare@univ-lyon1.fr
- Not yet recruiting
Hôpital Lyon sud, Endocrinology Diabetes Nutrition department
Pierre-Bénite, 69310
Berenice SEGRESTIN, +33 4 78 86 44 48, berenice.segrestin@chu-lyon.fr
About this study
Official title: 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.
Read more
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.
- Conditions
- Obesity (Disorder), Bariatric Surgery
- Being tested
- Nutritional counseling
- Keywords
- Bariatric surgery, gut microbiota, sensory alteration, food preferences, weight loss maintenance
- Medical subject headings
- Obesity, Food Preferences
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Nutritional counselingOther
Nutritional counseling
| Study group | Role | What they receive |
|---|---|---|
| Participants with nutritional counselling promoting gut microbiota diversity | Experimental | 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. Receives: Other: Nutritional counseling |
| Participants with standard nutritional counselling | No intervention | 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 being measured
The primary outcome is the main question the study is designed to answer.
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.
Measured: Primary outcome will be assessed three times : before the surgery, 6 and 12 months after
Secondary outcomes (99)
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.
Measured: 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.
Measured: 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
Measured: 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)
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: Before the surgery and at 6 and 12 month after
Sensory functions : detection scores
Assessed using Taste Strips tests
Measured: Before the surgery and at 6 and 12 month after
Sensory functions : intensity
Assessed using Taste Strips tests
Measured: Before the surgery and at 6 and 12 month after
Sensory functions : pleasantness
Assessed using Taste Strips tests
Measured: Before the surgery and at 6 and 12 month after
Sensory functions : edibility of tastes
Assessed using Taste Strips tests
Measured: Before the surgery and at 6 and 12 month after
Sensory functions : edibility of odors
Assessed using Taste Strips tests
Measured: Before the surgery and at 6 and 12 month after
Self-reported alterations in sensory functions
Assessed using dedicated questions
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: Before the surgery and at 6 and 12 month after
Endocrine, digestive or intestinal hormones
Blood sample to measure :
Adiponectin µg/ml
Measured: 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
Measured: Before the surgery and at 6 and 12 month after
Cardio-metabolic profile parameters
BMI will be assessed
Measured: Before the surgery and at 6 and 12 month after
Cardio-metabolic profile parameters
Energy metabolism by indirect calorimetry
Measured: Before the surgery and at 6 and 12 month after
Cardio-metabolic profile parameters
postprandial plasma markers: We will assess: glycaemia (g/L)
Measured: Before the surgery and at 6 and 12 month after
Cardio-metabolic profile parameters
CRP
Measured: Before the surgery and at 6 and 12 month after
Vital parameters
Blood pressure
Measured: 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
Measured: 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
Measured: Before the surgery and at 6 (except plasma fatty acid profile) and 12 month after
Nutritional status : Plasma fatty acid
Plasma fatty acid profile
Measured: Before the surgery and at 6 (except plasma fatty acid profile) and 12 month after
Nutritional status : Protein
Protein status
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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.
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: Before the surgery and at 6 and 12 month after
Changes in gastrointestinal symptoms
Assessed using Bristol stool scale
Measured: 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.
Measured: 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.
Measured: 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
Measured: 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.
Measured: 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).
Measured: 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.
Measured: until month 12
Eating behaviour during a standardised, filmed and validated ad libitum buffet: Meal microstructure
time spent selecting food at the buffet
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: Before the surgery and at 6 and 12 month after
Safety parameters
complete blood count
Measured: Before the surgery and at 6 and 12 month after
Safety parameters
AST
Measured: Before the surgery and at 6 and 12 month after
Safety parameters
ALT
Measured: Before the surgery and at 6 and 12 month after
Safety parameters
gamma GT
Measured: Before the surgery and at 6 and 12 month after
Safety parameters
bilirubin
Measured: Before the surgery and at 6 and 12 month after
Safety parameters
alkaline phosphate
Measured: Before the surgery and at 6 and 12 month after
Safety parameters
creatinine
Measured: Before the surgery and at 6 and 12 month after
Safety parameters
uric acid
Measured: 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
Measured: Before the surgery and at 6 and 12 month after
Safety parameters
coagulation : prothrombin time
Measured: Before the surgery and at 6 and 12 month after
Changes in stool frequency
Assessed using Likert scale
Measured: 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)
Measured: Before the surgery and at 6 and 12 month after
Changes in gastrointestinal symptoms
Assessed using Likert scale
Measured: Before the surgery and at 6 and 12 month after
Changes in gastrointestinal symptoms
gastrointestinal symptoms using GSRS
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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)
Measured: 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)
Measured: 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.
Measured: Before the surgery and at 6 and 12 month after
Cardio-metabolic profile parameters
postprandial plasma markers: We will assess: insulin (mU/L)
Measured: 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
Measured: 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
Measured: 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
Measured: 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
Measured: 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).
Measured: 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).
Measured: Before the surgery and at 6 and 12 month after
Cardio-metabolic profile parameters
Waist-to-hip ratio will be assessed
Measured: Before the surgery and at 6 and 12 month after
Vital parameters
resting heart rate
Measured: Before the surgery and at 6 and 12 month after
Safety parameters
coagulation : activated partial thromboplastin time
Measured: Before the surgery and at 6 and 12 month after
Safety parameters
coagulation : fibrinogen
Measured: Before the surgery and at 6 and 12 month after
Cardio-metabolic profile parameters
We will assess: total cholesterol (g/L)
Measured: Before the surgery and at 6 and 12 month after
Cardio-metabolic profile parameters
We will assess: HbA1c (mmol/mol),
Measured: Before the surgery and at 6 and 12 month after
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted5 Dec 2025
- Study start5 Nov 2025
- Primary completion5 Nov 2027 (estimated)
- Study completion5 Apr 2029 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Obesity (Disorder)Studies of the same condition, open and under way.
- More trials run by Hospices Civils de LyonThe 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
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- * Arm with nutritional counselling promoting gut microbiota diversity * Arm with standard nutritional counselling
- Masking
- Single blind
- Who is masked
- Participant
- Enrolment
- 60 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Hospices Civils de Lyon
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07268508
- Sponsor's protocol ID
- 69HCL24_0033
- Acronym
- BariaGut Taste
- Status last verified
- Apr 2026
- First submitted
- 14 Aug 2025
- Last updated
- 3 Apr 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 3 Apr 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- 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
- ClinicalTrials.gov ID
- NCT07268508
- Acronym / sponsor ID
- BariaGut Taste / 69HCL24_0033
- Conditions
- Obesity (Disorder), Bariatric Surgery
- Keywords
- Bariatric surgery, gut microbiota, sensory alteration, food preferences, weight loss maintenance
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 60 participants (estimated)
- Lead sponsor
- Hospices Civils de LyonUniversity, hospital or other
- Study start
- 5 Nov 2025 (actual)
- Primary completion
- 5 Nov 2027 (estimated)
- Study completion
- 5 Apr 2029 (estimated)
- First posted
- 5 Dec 2025 (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.
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 design
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (participant)
- Number of arms
- 2
- Model description
- * Arm with nutritional counselling promoting gut microbiota diversity * Arm with standard nutritional counselling
| Arm | Type | Receives |
|---|---|---|
| Participants with nutritional counselling promoting gut microbiota diversity | Experimental | Other: Nutritional counselingGiven 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. |
| Participants with standard nutritional counselling | No intervention | –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. |
Who may qualify
- Ages
- 25 to 65 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (6 listed)
- 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
Key exclusion criteria (14 listed)
- 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
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 |
|---|---|---|
| Nutritional counselingNutritional counseling | Other | Participants with nutritional counselling promoting gut microbiota diversity |
Primary outcome
Microbiota diversity 12 months after surgery
Time frame: Primary outcome will be assessed three times : before the surgery, 6 and 12 months after
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.
99 secondary outcomes
Eating behaviour during a standardised, filmed and validated ad libitum buffet : Food intake
Time frame: Before the surgery and at 6 and 12 month after
Eating behaviour during a standardised, filmed and validated ad libitum buffet: Nutritional quality
Time frame: Before the surgery and at 6 and 12 month after
Eating behaviour during a standardised, filmed and validated ad libitum buffet: Meal microstructure
Time frame: Before the surgery and at 6 and 12 month after
Eating behaviour during a standardised, filmed and validated ad libitum buffet: Meal appreciation
Time frame: Before the surgery and at 6 and 12 month after
Eating behaviour and preferences : Behaviors
Time frame: Before the surgery and at 6 and 12 month after
Eating behaviour and preferences : Food preferences
Time frame: Before the surgery and at 6 and 12 month after
Appetite : hunger level
Time frame: Before the surgery and at 6 and 12 month after
Appetite : satiety
Time frame: Before the surgery and at 6 and 12 month after
Appetite : desire to eat
Time frame: Before the surgery and at 6 and 12 month after
Appetite : prospective consumption
Time frame: Before the surgery and at 6 and 12 month after
Appetite : meal appreciation
Time frame: Before the surgery and at 6 and 12 month after
Sensory functions : detection scores
Time frame: Before the surgery and at 6 and 12 month after
Sensory functions : intensity
Time frame: Before the surgery and at 6 and 12 month after
Sensory functions : pleasantness
Time frame: Before the surgery and at 6 and 12 month after
Sensory functions : edibility of tastes
Time frame: Before the surgery and at 6 and 12 month after
Sensory functions : edibility of odors
Time frame: Before the surgery and at 6 and 12 month after
Self-reported alterations in sensory functions
Time frame: Before the surgery and at 6 and 12 month after
Body perception
Time frame: Before the surgery and at 6 and 12 month after
Appetite : desire to eat
Time frame: Before the surgery and at 6 and 12 month after
Appetite : prospective consumption
Time frame: Before the surgery and at 6 and 12 month after
Microbiota composition
Time frame: Before the surgery and at 6 and 12 month after
Microbiota function
Time frame: Before the surgery and at 6 and 12 month after
Endocrine, digestive or intestinal hormones
Time frame: 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
Time frame: Before the surgery and at 6 and 12 month after
Cardio-metabolic profile parameters
Time frame: Before the surgery and at 6 and 12 month after
Cardio-metabolic profile parameters
Time frame: Before the surgery and at 6 and 12 month after
Cardio-metabolic profile parameters
Time frame: Before the surgery and at 6 and 12 month after
Cardio-metabolic profile parameters
Time frame: Before the surgery and at 6 and 12 month after
Vital parameters
Time frame: Before the surgery and at 6 and 12 month after
Nutritional status: Blood vitamin
Time frame: Before the surgery and at 6 (except plasma fatty acid profile) and 12 month after
Nutritional status : Blood mineral
Time frame: Before the surgery and at 6 (except plasma fatty acid profile) and 12 month after
Nutritional status : Plasma fatty acid
Time frame: Before the surgery and at 6 (except plasma fatty acid profile) and 12 month after
Nutritional status : Protein
Time frame: Before the surgery and at 6 (except plasma fatty acid profile) and 12 month after
Average energy
Time frame: Before the surgery and at 6 and 12 month after
macronutrients intakes and proportions
Time frame: Before the surgery and at 6 and 12 month after
micronutrients intakes and proportions
Time frame: Before the surgery and at 6 and 12 month after
Mental health: Quality of life
Time frame: Before the surgery and at 6 and 12 month after
Mental health: Self-confidence
Time frame: Before the surgery and at 6 and 12 month after
Mental health: Depression
Time frame: Before the surgery and at 6 and 12 month after
Mental health: Anxiety
Time frame: Before the surgery and at 6 and 12 month after
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 3 Apr 2026.
Related trials for Obesity (Disorder)
RecruitingObservational study
Endoscopic Sleeve Gastroplasty (ESG) Prospective Trial for Obesity (EGO-Trial)
Obesity
Active, not recruitingPhase 4
Effects of Sequential Therapy With Mexidol® (Intravenous) and Mexidol® FORTE 250 (Oral) on Functional Brain Activity Assessed by Functional Magnetic Resonance Imaging and Biochemical Parameters in Patients With Chronic Cerebral Ischemia: A Comparison of Patients With and Without Metabolic Disorders
Metabolic Abnormalities, Obesity & Overweight
Recruiting
Exercise Training and Vitamin D Metabolism
Obesity & Overweight, Vitamin D
Recruiting
Metabolic Health, Bones and Nuts During Weight Loss in Adults
Weight Loss, Bone Density
Active, not recruiting
Effect of Probiotics on Insulin Sensitivity in Overweight and Obese Pregnancy
Obesity & Overweight, Gestational Diabetes Mellitus (GDM)
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.
Berenice SEGRESTIN contact
3 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Nutritional counseling in people with Obesity (Disorder) and Bariatric Surgery, run by Hospices Civils de Lyon at 3 sites in France.
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 6 inclusion and 14 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 3 Apr 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 3 sites in France. 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?
Contact Julie-Anne NAZARE (+33 6 88 87 09 62, julie-anne.nazare@univ-lyon1.fr), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Microbiota diversity 12 months after surgery (time frame: Primary outcome will be assessed three times : before the surgery, 6 and 12 months after). 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 3 Apr 2026.