Caffeine consumption relates to metabolism by acting as a stimulant that can enhance energy expenditure and fat oxidation. It increases adrenaline levels, which can temporarily boost metabolic rate and improve exercise performance, making it a popular choice among athletes. However, excessive caffeine can lead to adverse effects like jitteriness or insomnia, which can counterproductively affect overall health and performance. Moderation is key, and understanding individual responses to caffeine will help maximize its benefits while minimizing negative impacts on metabolism and fitness outcomes.