Julia;41978 wrote: Our bodies will excrete what is not used. You can not overdose on it.
Even if the body excretes what is not used, there will be a temporary overdose in the bloodstream. This may have various side effects, the most common one being disturbance of other processes that would seem unrelated at first sight. Even if the bloodstream overdose is only temporary, that does not mean it is by defintion harmless.
The next thing is the excretion. Depening on what you overdose, excretion may or may not involve some chemical processing in the liver. The intermediate products that are created during this processing may be harmful. One example is formaldehyde, but there are many more.
Finally, whether the overdose is excreted through the liver or through the kidneys, these organs do have to work much, much harder than under healthy circumstances. Taking an overdose may severely stress the liver and the kidneys, to the point of either poisoning or exhausting them.
Oh, I almost forgot to ask you to think about where your “excretions” are going. You guessed it: you flush them down the toilet. This burdens the envirenment with high levels of all kind of stuff that does all kinds of things to unsuspecting plants, animals, and humans.
In summary: stating that “you cannot overdose because the body just excretes what is not used” is a harmful and overly simplistic view of reality.