HIIT, or high-intensity interval training, is a type of cardio exercise that involves short bursts of high-intensity exercise followed by periods of rest or low-intensity exercise. Some research suggests that HIIT workouts may be more effective in promoting fat loss than traditional cardio due to the 'afterburn' effect or EPOC (excess post-exercise oxygen consumption). However, both traditional cardio and HIIT can be effective in promoting weight loss when combined with proper nutrition and weight training.