I agree. It is ironic that coffee was brought up, because that was one of the biggest couple items of diet that I really had to eliminate. Coffee (caffeine), sugar, and processed foods are a big no no - at least for when you feel bad.
As I have gotten better, I will now occasionally test myself by ingesting a small amount of sugar - maybe a pop once in a great while just to see how I am doing. And I am better! It does not affect me and it shouldn't. I refuse to feel guilty about having a tiny bit of this or that here and there, when i read about the average american and the pounds of sugar he or she eats every year! I forgot the actual figure, but I will say that I maybe eat 5 to 10% of that a year now.