The Mythology: Increases endurance and capacity for intensity. Burns the fat.
The Truth: Reduces fatigue and improves performance, but not everyone benefits.
Research: Caffeine is the most widely used drug in the world and despite decriers its safety profile is enviable. The research regarding endurance sports is unanimous. Yes it works and works well. Marathoners with a Red Bull fix will definitely be able to run longer than their non-caffeinated brethren. The difficulty is with short, high intensity activity like weight lifting and sprinting.