[smart (OP)]

I noticed that in order to fully enjoy coffee, I must eat something good before. So I started to eat before everytime I drink coffee, without any side effects.

Any ideas how caffeine may improve digestion and enhance metabolism of carbohydrates?

What do you think?

[wolfekeeper]

So far as I know coffee triggers the release of sugars from your liver, and that's one reason you feel more lively when you've had a cup.

However, if you're hungry then the glycogen stores in your live (i.e. glucose stores) may be running low, and in that case your body will release hormones to create glucose from other sources, such as breaking down muscle; which will make you feel bad and make you feel even more hungry.

Anyway that's my rough understanding.

[chiralSPO]

I will suggest two possible explanations:

1) Caffeine increases the metabolism, which means more available energy when you have plenty of blood sugar available. But if you already have low blood sugar then it may fall even lower, feeling not so great.

2) Coffee is more than just caffeine. The drink itself contains hundreds of organic compounds, several of which are quite irritating to the GI tract. In my experience, having a pot of strong coffee on an empty stomach is a sure-fire way to get the runs real bad... However, I have found that this prblem is minimized when coffee is taken with or just after a decent meal.