The invention relates to a controllable stomach band (1) comprising a non-extendible rear (4) and a chamber (2) which is arranged on the stomach-side of the rear (4) and is used to control the restriction of the stomach by the supply or discharge of a liquid or a fluid into or out of the chamber (2). The aim of the invention is create one such stomach band (2), with which, during a corresponding rise in pressure in the stomach-restricting chamber (2), triggered for example by the passage of a swallowed bolus, the stomach can be temporarily enlarged to enable the bolus to pass easily and liquid to flow out via the stomach opening. To this end, a pressure chamber (6) is provided outside the rear (4), said pressure chamber being connected to the stomach-restricting chamber (2) by means of a pressure valve (5).
