HIIT (high intensity interval training) is one of the most effective methods to reduce fat.

It is recommended that HIIT high intensity interval training is carried out immediately after getting up.

HIIT is also particularly good for bodybuilders. Let us look for example at a sprinter, his body is virtually fat free but still muscular. In contrast, a long-distance runner who trains mostly in endurance,  has little muscles.
Another benefit of HIIT is that the units-intervals can take up to 20 minutes. One can make the intervals very flexible (eg 30 sec-1 min;. 10 sec-20 sec).

The interval time should last between 30 and 90 seconds, the pause should be 2:1 (advanced 1:1) to stand.

Example of a HIIT:

Beginners: run for 30s and rest for 60s

Advanced: run for 30s and rest for 30s

Both in the intervals and in the breaks, it is important to maintain a smooth pace. It is best to run in the wild,as it is more flexible because of the movement speed. To prevent injury you should warm up thoroughly beforehand.
Beginners should choose a short interval of time and they should sprint easily. Over time, you can then increase the interval time, and eventually reduce the interval to-pause ratio of 1:1.
Finally, only one remains to say: The system sounds simple and loose, but that is deceptive. HIIT is extremely stressful, and therefore not suitable for beginners.