For me I was on a business trip where I fell ill prior to the flight home. Lets just say that it wasn't pretty, my girlfriend picked me up from the Airport struggling to stand up. The next week I wasn't able to eat anything surviving on water.
Seeing that I consumed an unhealthy amount of coffee daily, and how I hadn't had one in a week, I decided to make the break while I could. I was already weak from what ever I had picked up on that trip, but it was nothing to the next few weeks. I was lucky to only get mild headaches, but the lethargy and the sleepless nights drove me insane.
Having read this article, I'm now re-thinking what I eat as well. I too challenge the heat of my curries... and thanks to desk jobs I don't get out that much. Looks like I'll be changing things shortly.
One kicker that has happened to my health since this change, an ailment that I had never had prior to the removal of coffee, has caffeine as a way to help reduce the effects. My body... hates me.