The days of endlessly grinding away at long duration, low intensity aerobic exercise to burn fat are gone. Isn't that what you were told to do back in the 80's and 90's? Long duration aerobic exercise burns fat, while weight training makes you bulky and tight. Well, both are crap, and we have come a long way in exercise science to better understand how the body utilizes fat for fuel. The fact is, your body composition will become much leaner if you regularly engage in high intensity interval training.
Never heard of the Tabata Protocol? Created by Izumi Tabata, the Tabata Protocol is simply the best supra-aerobic cardio workout every discovered. As Dr. Tabata states, "the rate of increase in V02max is one of the highest ever reported. Fat burn is greater when exercise intensity is high. With only 8 minutes (give or take) every 3 days, you can turn your body into a fat-burning super-engine." And while that may be a bit dramatic, the science is solid. Short duration, high intensity intervals will lead to serious decreases in bodyfat over time, and the Tabata Protocol is just one of many such version of interval training.
Putting it into practice is simple. Pick a few exercises that involve a lot of muscle, like swings, squats, snatches, pushups, and pullups. Perform 20 seconds of an exercise, rest 10 seconds, and repeat for at least 8 intervals. Every 20 second work period can be the same exercise, or you can make them different exercises, as in a circuit training routine. The bottom line is, try to find a way to use it in your training, as it is a powerful tool, and works great when you only have 10 minutes to train!
Here is a sample video of using the Tabata Protocol with kettlebells: