There's a lot of research on HIIT!
Proven to Burn Fat
Research shows that HIIT burns more subcutaneous fat than low-intensity cardio training by increasing your metabolic rate. This type of fat makes up most belly fat that sits right under the skin. Additionally, high intensity interval training has been shown to yield higher excess post-exercise oxygen consumption (EPOC), which means you'll still be burning calories up to 24 hours after your workout has ended. Studies have shown that, of the calories burned with a HIIT workout, up to 95% of those calories burned occur after the workout.