You are right in your case. I really like Gerson's approach, and as a matter of fact I use coffee enemas almost every day, even when I don't fast. They are such amazing tools for liver cleansing.
But my situation is different. I am healthy and clean, generally, without any vitamin and mineral deficiencies. So, when I get sick like that, I just use it as an opportunity to start my water-only fast. Because I actually love water-only fasting. I use it as an excuse to have my lovely coffee enemas more often. LOL! :-)