Figure 2.

Example of a nonlinear feedback-gain function. The DIPM [6,7] posits that the body-weight regulatory system has thresholds for minimum weight gains and losses required to stimulate weight-regulatory responses and has separate control mechanisms for gains and losses. As the figure shows, a simple negative-feedback system with a curvilinear feedback-gain function and no set-point can result in the same phenomenology. In this example (although not posited by DIPM), the slope of the feedback-gain (and hence, appetite) is greater for weight loss than weight gain. Stronger feedback gain increases response speed and intensity and reduces steady-state changes.