Yes, definitely - I could be wrong, but I've been told that when you're healthier, your body metabolizes things faster & more efficiently. So stuff like alcohol or caffeine will hit you harder and faster too (all the more reason, right?).

For myself, I've noticed that after getting healthier, just one cup of coffee a day keeps me plenty productive. I might have a cup of tea in the afternoon. But it's a far cry from my previous 3-cups-a-day habit.