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.
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
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
Parallel
Nutritional counseling
Other interventionNutritional counseling
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.
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.
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.
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
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)
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