Caffeine is indeed the most widely used stimulant in the world, whether in the form of black coffee or in supplements that contain it. Its function lies in stimulating the nervous system to increase alertness and energy levels. By delaying fatigue, it directly enhances our performance, whether in sports or any other activity. In addition to that, caffeine also accelerates the breakdown of lactate in the muscles and indirectly promotes the utilization of fat as an energy source. This is why caffeine is a common ingredient in fat burners.