The invention relates to a prosthetic device intended for being implanted in a patients gastrointestinal tract, said device comprising:an inflatable gastric balloon, the volume of which is modulatablea duodenal prosthesis comprising a pre-pyloric flange and a flexible tubular body.According to the invention, such a device is characterized in that it comprises a system for coupling said balloon to said duodenal prosthesis said duodenal prosthesis is compressible and expandable in a radial direction said prosthesis has a wall that is fixedly attached, on at least one part of its length, to a helical frame and said helix has an irregular pitch.
