Is drinking coffee on an empty stomach actually considered harmful? I do it daily every day of the week. My first meal of the day is lunch a few hours after I've had either an Americano with 2-3 shots of espresso, or a regular coffee with 1-2 espresso shots in it. Almost always black.

On a low carb diet, I get GI distress generally after eating lunch, but outside of dieting I haven't noticed any adverse effects related to it. I've been doing this every weekday for over 2 years now.