So, here is a common one:
To burn body fat you need to perform low-intensity cardio for a long time. First of all, any exercise is better than none, but higher intensity may be more efficient. You may be misled by seeing the "fat loss heart rate zone"on the treadmills at the gym. You burn about 50/50 fat/carbohydrates at rest. With low-intensity exercise, you will burn a greater percent of your calories from fat, but the rate that you burn calories is low compared to higher intensity exercise. You do burn a greater percent of carbohydrates with high-intensity exercise, as fat is inhibited and not efficiently mobilized, transported, and metabolized.
Walking Slow: 60% fat, 40% carb, at a rate of 4 Cal / min.
Total fat burned= 2.4 Cal/min
Running Hard: 25% fat, 75% carb, at a rate of 15 Cal/min
Total fat burned= 3.5 Cal/min PLUS the fat you will burn to restore your glycogen supply over the next 24 hours.
So, your body is always burning fat, and shifts to using more carbohydrates when the conditions demand a greater rate of energy production. Higher-intensity exercise (whether it is running, swinging kettlebells, or lifting weights) will, in the long-run, burn fat more efficiently (and is more fun). Of course, if you are a beginner, you will need to start at a lower intensity and condition your body to tolerate higher-intensity exercise.