HIGH INTENSITY INTERVAL TRAINING High Intensity Interval Training (HIIT) has become a popular way to burn more fat. It's a training method that has been effective for many people. HIIT is a training idea in which low to moderate intensity intervals are alternated with high intensity intervals. HIIT can be applied to running or to exercises such as squatting. HIIT is considered to be much more effective than normal cardio because the intensity is higher and you are able to increase both your aerobic and anaerobic endurance while burning more fat than ever before!