Your body drops weight quite fast when you dive into a new cardio regimen; a good hour on the treadmill on a hill-setting can easily torch 600–700 calories per hour. However, just like any other exercise, if it’s done consistently and religiously, the exercise can become too easy and your body will adapt (therefore, burning less fat in the process). Try increasing your per kilometer pace by 15-20 seconds, and you should be a little breathless after 5k. Also, do something totally different, such as using cardio rope or flipping truck tires. The different motions will definitely produce a harder and more challenging cardio workout which should allow you to lose fat fast