A device for treating obesity by limiting absorption of food through a wall of a duodenum of a patient includes a sleeve (10, 10, 20, 21, 30, 40, 50, 60, 70, 80, 90) inserted into the duodenum of a patient. The sleeve includes a plurality of first blocking areas (16, 16, 23, 37, 42, 52, 54, 62, 64, 65, 70, 72, 74, 82, 84, 92, 94) and a plurality of first food absorption areas (18, 28, 38, 46, 56, 66, 76), the first blocking areas providing duodenum wall covers to prevent food absorption through the duodenum wall and the first blocking areas together defining a first total blocking area. The first food absorption areas provide access to the duodenum wall to enable food absorption through the duodenum wall and the first food absorption areas together defining a first total absorption area.
