eA represents the amount of a substance that perturbs one of the body's negative feedback loops. The amount oscillates between 0V & 100V.
eR represents the effect of the substance on the body. 100V represents maximum effect and -100V represents maximum anti-effect.
The very first time that the substance is taken, there is 100V of effect. As the time-constant of the negative feedback loop starts to "kick-in", the effect diminishes. Just before the substance is discontinued, the effect is only 36.8V. Just after the substance is discontinued, the anti-effect is -63.2V. If the input continues to oscillate between 0V & 100V, the effect & anti-effect eventually become equal in magnitude. This is known as "cycling".
If the substance is applied continuously, the effect diminishes until, at some point, the effect is 0V. When the substance is discontinued, the anti-effect is -100V initially, but diminishes to 0V.
This is analogous to drug tolerance, dependency & withdrawal, where eventually, the user has to take the drug just to feel normal, and discontinuing the drug gives the worst withdrawal symptoms ever, initially. After the drug has been discontinued for a while, the withdrawal symptoms diminish to zero.
The above also applies to supplements that perturb one of the body's Hypothalamic Pituitary NFB loops e.g. the HPA (Adrenal), the HPT (Thyroid) or the HPG (Gonadal) axes, or any other system (as everything in the body is regulated by a negative feedback loop).
This explains why a supplement can work really well at first, then its effect becomes weaker & weaker, until there is no effect at all. The body has compensated for it.