20 minutes and 3 kilometers is not enough, at least 40 minutes and 5 kilometers. Why? Because the human body began to consume fat in aerobic exercise for about 40 minutes, it only consumed glycogen before. So if you want to lose weight, the longer you run, the better. Not for strength, just for time. You can run for 5 minutes and walk for 5 minutes, so it's not so painful, as long as you keep your heart rate around 160.