High-intensity interval training (HIIT) significantly impacts metabolism by increasing the rate of calorie burn both during and after workouts. The intense bursts of activity followed by short rest periods elevate heart rate, leading to an effect known as excess post-exercise oxygen consumption (EPOC), where the body continues to burn calories even at rest. This metabolic boost aids in weight loss and fat loss. Additionally, HIIT improves cardiovascular fitness and enhances insulin sensitivity, contributing to overall metabolic health and making it an efficient training approach for those looking to maximize their workouts.