1. Under normal circumstances, when we haven't eaten for 6- 10 hours (from dinner the day before to the next morning), by the morning, the glycogen reserves in our bodies (the carbohydrates we eat are stored in the form of glycogen) have almost been exhausted. When the concentration of glycogen is low, the body will decompose fat to supply calories, so aerobic exercise can directly consume fat at this time. This is the theoretical basis of fasting aerobic, but only for the reduction of body fat.

2. Fasting for a long time in the morning will cause another situation: cortisol levels will rise, which will lead to muscle consumption. Cortisol: It is a hormone secreted by ourselves. Under normal circumstances, the body can control the cortisol content in the blood. However, in the morning, the cortisol level is very high. High cortisol level will break down muscles to provide energy for the body, which is simply a hormone that will make you lose muscles.