FIELD: medicine.SUBSTANCE: group of inventions refers to the field of medicine and is designed to reduce excess body weight. Apparatus for reducing the amount of materials absorbed in the gastrointestinal tract comprises one or more elements from a compressible absorbent matrix material having a spongy structure. In the spongy structure, there are many cells formed by the walls of the cells. Material of said matrix is functionalized with functional groups having high hydrophilicity and packed in compressed space in such a way that the volume of material in the compressed state is less than 50 % of the volume of the material of said matrix in the expanded state. Said material is capable of absorbing the digestible material in the stomach by an action that triggers the expansion of the material of the compressible absorbent matrix from the compressed state to the expanded state. Change in the state from the compressed to the expanded causes the curling and folding of the material of the compressible absorbent matrix, so that the digestible material in the stomach is absorbed. Absorbable digestible material is retained in the material of the compressible absorbent matrix. Material of the compressible absorbent matrix further comprises one or more additional compounds including hydrogels, wherein one or more additional compounds retain the digestible material in the compressible absorbent matrix material by forming a seal that prevents absorption of the digestible material in the stomach. In another embodiment, a method is provided for isolating nutrients or compounds from absorption in the digestive tract, which includes swallowing the device. In yet another embodiment, a method for treating obesity is provided, which comprises providing said device to an obese subject. Also a food product that contains said device, and a kit for reducing the amount of materials absorbed in the gastrointestinal tract are provided.EFFECT: use of a group of inventions makes it possible t
