Abstract: The invention relates to novel a high-volume swelling hydrogel which comprises a plurality of pores which are defined by an interpenetrating network, and/or a semi-interpenetrating network and/or simple cross-linked arrangement of a plurality of one or more species of hydrophilic polymers, optionally together with one or more biocompatible polymers and optionally together with one or more plasticising agents, characterised in that at least some of the pores are at least partially collapsed and/or flattened, and further characterised in that the interpenetrating network and/or semi-interpenetrating network and/or cross-linked arrangement which defines the collapsed and/or flattened pores is substantially unbroken. The invention also relates to a process for preparing such hydrogels, and to their use as an appetite suppressant.