| Abstract: Programs of food or water restriction allow experimenters to control consumption and maintain the animals' weight at its predetermined level. These programs have been often employed (a) to produce an increase in general activity, (b) to control body weight, usually around 80% of the initial weight, (c) guarantee an adequate motivational level, and (d) to maintain the stability of experimental parameters. The literature suggests that ending a restriction program affects an organism's feeding patterns and therefore its body weight. Our results confirm that interrupting a regular or variable program of food or water restriction induces an increase in body weight above that registered in baseline. We have also identified a post-deprivation effect characterized by a striking increase of food or water intake, which suggests an underlying regulatory mechanism. Also, we have consistently observed self-restriction of the freely available commodity during restriction of the complementary commodity (be it food or water). These effects are present independently of experimental history, sex, type of the restriction program, previous body weight, nature of the commodity under restriction (food or water), and the presentation schedule (regular or irregular) of restriction periods. These findings are relevant to the control of alimentary disorders such as bulimia. |