Set points or settling points for body weight?: A reply to Mrosovsky and Powley

Mrosovsky and Powley have recently argued that the term set point is a useful concept for describing the fact that body weight is maintained at a relatively constant value and is defended against challenges. This reply takes the position that the term set point, which refers to an input variable in a control system, should be used only as an input variable and then only when there is evidence that such a reference variable exists. Since stability of a controlled system can be maintained by a regulatory system which does not contain a set point the use of this term implies a particular type of control and should only be used when there is evidence for its existence.