The present invention relates to a regulating device (1) for regulating a fluid flow, the regulating device (1) comprising an actuator element (3) which is provided with a flow area (4) arranged to convey fluid between a fluid inlet (9) and a fluid outlet (13) and which includes a first restriction device (17), and a regulating device body (5) which is disposed at least in a portion of the flow area (4) and which is provided with a second restriction device (19) forming, together with said first restriction device (17), the restriction unit or choke device (17, 19) of the regulating device (1), the actuator element (3) and regulating device body (5) being arranged to move freely independently of each other as a consequence of a material expansion or material contraction, the throughput of the choke device (17, 19) being influenced by an energy source (21) which is arranged to supply energy to at least one of the actuator element (3) and/or regulating device body (5). Also described are methods of using the regulating device (1). The regulating device (1) is also suitable for use as a flow meter.