HIIT workouts are all the rage, due in part to their fat-busting benefits. HIIT stands for High Intensity Interval Training. You do short bursts of intense exercise, take a brief breather, and rev it up right away. Your heart-rate accelerates leading to fat burn that goes beyond the average workout. One theory highlights how HIIT improves insulin sensitivity, which aids in loss of fat. One amazing HIIT workout to try is F45. Started in Australia, this studio-based HIIT program is taking the world by storm. Not only is it fun, but you’ll burn fat fast.