Whew good to know it is the caffeine. I take capsules, coffee just doesn't agree with me for some reason. I'd much rather tough out the hunger pangs than deal with the coffee turning my gut into a percolating disaster.
Rob, FWIW I can't drink black coffee on an empty stomach either, but adding heavy whipping cream (enough to turn it light brown) makes all the difference.
If I don't drink coffee for a while, if fine. It seams as though once I get used to it after a week or so, no matter how I drink it I feel like crap. I've never been a coffee drinker. Only started later in life when I needed a bump before hitting the gym. Maybe some sort of an allergy I'm guessing.