60 patients scheduled for bariatric surgery will be included into 3 categories (20 patients with non complicated obesity, 20 patients with metabolic syndrome and 20 patients with a type 2 diabetes or hypertension). 20 volunteers will be enrolled as normal referents. The patients and the volunteers will have a classical pre-operative check-up (fibroscopy, oesophageal pHmetry and manometry) and extra investigations as isotopic gastric empty exam, lactulose oro-caecal transit exam, intestinal permeability test calculated by lactulose-manitol ratio urinary excretion. Intestinal and colonic biopsies will be also provided for studying permeability. For only patients, samples from the gastric resection will be provided for analysing the enteric nervous system and motricity.

Patients:

Patients must be aged between 18 and 65 years old with a BMI>40kg/m2 for non complicated patients or with a metabolic syndrome and with a BMI>35kg/m2 for patients with type 2 diabetes or hypertension. They must be eligible for bariatric surgery.

Patients with a type 1 diabetes, neurologic or neuro-degenerative disease will be excluded.

Volunteers:

Volunteers must be aged between 18 and 65 years old with a BMI between 20 and 25kg/m2 Men and women are eligible.