It is logical to assume that if the body were able to eliminate the toxins, they wouldn't have built up in the first place. We tend to eliminate toxins slowly because there is a dynamic turnover in the body, and cells are usually destroyed and remade over time. Again, there is little evidence. Take lead, for example. We have the ability to rid ourselves of this mineral, albeit slowly.
Health problems occur when our lead intake exceeds the body's purifying abilities.
It's then that lead builds up and turns into a dangerous toxin. I view this as the real goldmine. The fast can serve as a productive time of contemplation, where one is free to review the status quo and define the quality of life at the other end. I think it can be powerful, as it defines a distinct separation from what was and what is to be. I hope these additional comments are of value.