System comprising a gastrointestinal implant with a first and a second fastening means (3, 4) and an apparatus for positioning said system in the human gastrointestinal tract, wherein the apparatus comprises the following: - an outer vessel having a first longitudinal axis - an inner supporting body arranged inside the outer vessel and having a second longitudinal axis - a first mounting position arranged between outer vessel and inner supporting body for the first fastening means - a second mounting position arranged between outer vessel and inner supporting body for the second fastening means, wherein - the outer vessel is separable from the inner supporting body, can preferably be withdrawn axially in the direction of the second longitudinal axis and the gastrointestinal implant comprises as follows: - a tubular element, embodied to transport chyme through at least one section of a human intestine; - a first fastener, which is connected to the tubular element and has a flow opening, the first fastener being designed to be positioned in a section of a duodenum adjacent to a pylorus - a second fastener, which is connected to the tubular element or to the first fastener and has a flow opening, the second fastener being designed to be positioned in the pyloric antrum, - a connecting element that connects the first fastener or the tubular element to the second fastener, wherein first and second fastening means (3, 4) are threaded on the inner supporting body and are position-fixed in the first and second mounting positions (3a, 4a) respectively and are compressed to a first size and/or assume a first position, and upon removal of the outer vessel expand to a second size and/or assume a second position that is different from the first position, characterized in that a section of the inner supporting body is constructed with a reduced cross-sectional area compared with sections (50, 51) adjacent to this section, and that grooves (15, 16) that form the mounting positions (3a, 4a) are arranged in this section, in which grooves the two fastening means (3, 4) are at least partially accommodated and one section of each of the fastening means (3, 4) is folded in the direction of the longitudinal axis of the inner supporting body. - an outer vessel having a first longitudinal axis - an inner supporting body arranged inside the outer vessel and having a second longitudinal axis - a first mounting position arranged between outer vessel and inner supporting body for the first fastening means - a second mounting position arranged between outer vessel and inner supporting body for the second fastening means, wherein - the outer vessel is separable from the inner supporting body, can preferably be withdrawn axially in the direction of the second longitudinal axis and the gastrointestinal implant comprises as follows: - a tubular element, embodied to transport chyme through at least one section of a human intestine; - a first fastener, which is connected to the tubular element and has a flow opening, the first fastener being designed to be positioned in a section of a duodenum adjacent to a pylorus - a second fastener, which is connected to the tubular element or to the first fastener and has a flow opening, the second fastener being designed to be positioned in the pyloric antrum, - a connecting element that connects the first fastener or the tubular element to the second fastener, wherein