Hmm, I didn't realize not eating had something to do with it.
I never eat breakfast, so the coffee keeps me regular. For example, today I went into work with an extra large coffee which I drank in about thirty minutes. One hour after that I was running to the toilet.
It also gives me quite a large amount of gas, which is awesome. Being able to repell the co-workers at any given moment is a blessing.
Weird...Do you smoke by any chance? Coffee has never affected me like that, and i drink several cups a day. I used to get the same reaction first thing in the morning if I drank a glass of cold water on an empty stomach, but i haven't had that problem either since I quit smoking. My metabolism seems to be a lot slower now than it was when I smoked. The downside is that I've gained weight... prolly cause I am so full of sh*t now. LOL