Unsafe, mostly hormones, will rebound. For weight loss, morning running is a good aerobic exercise to lose weight. This is because after a night's sleep, glycogen in the body has been consumed in large quantities, which is conducive to fat mobilization. In order to avoid hypoglycemia, just add a small amount of sugar, such as about 5 grams of sugar water. If you plan to run in the morning to lose weight, but you have a full breakfast or run on an empty stomach after waking up, you may run in vain.