Treadmill belongs to aerobic exercise, and the first 20 minutes of aerobic exercise mainly consume blood sugar. If you keep the heart rate of reducing fat all the time, fat will gradually participate in it after 20 minutes, but fat and blood sugar are always consumed together, which is only a matter of proportion.

Namely:

The main energy source for the first 20 minutes: blood sugar.

20- 120 minutes main energy source: blood sugar+fat (blood sugar drives fat, both of which are always consumed together).

Therefore, when running a treadmill, it usually takes more than 20 minutes to reduce fat, because at first, the body consumes mainly food sugar, and after 20 minutes, it will slowly consume fat. It is advisable to take 40-90 minutes, and it is best not to stop halfway; But don't exceed 120 minutes, because the blood sugar is too low at that time, which is not conducive to fat decomposition. People will feel very hungry, it is difficult to continue exercising, and they want to stop and have a rest. If you are still struggling at this time, people with poor health may faint or even die suddenly; People with good physical fitness, even if they can persist in running down, will also cause the loss of muscle protein.