To get lean you've got to strip off your body fat. To strip off your body fat you've got to burn calories. And to burn calories you've got to exercise - and that means cardio (it all means weight training, but we'll get to that later). For decades there's been this huge debate in the fitness world about whether short, fast cardio or long, slow cardio will shred the fat the fastest. Well, the debate is over and the winner is short, fast cardio. Specifically, the most effective form of cardio exercise known to man is High Intensity Interval Training. Let's find out why . . .