Fron Healthbolt (via Mtanga):
- In The First 10 minutes: 10 teaspoons of sugar hit your system. (100% of your recommended daily intake.) You don’t immediately vomit from the overwhelming sweetness because phosphoric acid cuts the flavor allowing you to keep it down.
- 20 minutes: Your blood sugar spikes, causing an insulin burst. Your liver responds to this by turning any sugar it can get its hands on into fat. (There’s plenty of that at this particular moment)
- 40 minutes: Caffeine absorption is complete. Your pupils dialate, your blood pressure rises, as a response your livers dumps more sugar into your bloodstream. The adenosine receptors in your brain are now blocked preventing drowsiness.
Even more here.