Adaptation of Human Gut Microbiota to Energetic Restriction
Condition: Obesity; Metabolic Diseases; Nutrition Disorders; Body Weight
MeSH terms: Obesity; Metabolic Diseases; Nutrition Disorders; Body Weight
Study type: Interventional

Summary: 
      Gut microbiota ecology is altered in obesity and could link obesity and its complications.
      Bariatric surgery enables a major and sustained weight loss therefore improving obesity
      related disease.

      the investigators primary aim is to evaluate gut microbiota adaptation to weight loss and the
      specific role of energetic restriction. Furthermore we aim to compare gut flora of obese
      patients post bariatric surgery to that of lean healthy volunteers.

      Thus, the investigators plan to compare gut microbiota from 140 obese individuals before and
      after either restrictive (gastric banding) procedures or gastric bypass procedures to that of
      40 lean healthy volunteers at baseline.
    

Detailed description: 
      The prevalence of obesity is rising to an epidemic level. Yet medical and pharmacological
      treatments have proven their limits. Dietetic modifications contribute to adipose tissue
      alterations and cross talk dysfunction with other tissues linked to weight maintenance. In a
      previous study in a model of abrupt weight loss 6 months after Roux-en-Y Bypass, the
      investigators observed a rapid adaptation of the dominant gut microbiota. Conversely some
      species were directly linked to the improvement of low grade inflammation independently of
      calory intake.

      Therefore the investigators hypothesized that gut microbiota in obese patients could link
      food consumption with obesity alterations such as metabolic impairments, energetic storage
      dysfunction and increased systemic and adipose tissue inflammation.

      The investigators want to address the specific role of energetic restriction in gut
      microbiota modification after weight loss.

      To answer that question the investigators will evaluate gut microbiota composition before and
      during the first year after either gastric banding or gastric bypass surgery. they also aim
      to evaluate whether gut flora post surgery evolves toward that of lean healthy subjects Our
      study has several objectives. The investigators also aim to assess whether gut microbiota
      modification is associated with systemic and tissue inflammation reduction and metabolic
      improvement during the follow up.

      This project is based on a clinical protocol performed in massively obese subjects (BMI>40
      kg/m²). The investigators plan to recruit 70 obese patients addressed for gastric banding and
      70 candidates for gastric bypass. Clinical phenotype, biochemical analysis, body composition,
      systemic and adipose tissue inflammation, endotoxemia and gut microbiota will be assessed at
      baseline and 1, 3 and 12 months after surgery. Specific food consumption will be recorded at
      every time point. A group of 40 lean healthy volunteers will undergo the same phenotyping.

      Associations between all these clinical and biological parameters will be assessed at the
      different point of the follow up.

      More generally, this project might lead us to elucidate a new function of gut microbiota and
      eventually consider novels anti obesity therapeutic strategies
    

Intervention name(s): stools sampling; adipose tissue biopsy
Intervention type(s): Other; Other
Intervention description(s): stools sampling at baseline, 1, 3 and 12 months; surgical adipose tissue biopsy during surgery, 1, 3 and 12 months
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Other
Keywords: Obesity; adipose tissue inflammation; Low grade systemic inflammation; gut microbiota; Bariatric surgery