Girls should lose weight two weeks before menstruation. Two weeks before menstruation, the secretion of estrogen and progesterone reaches the highest level, which can promote the body to convert fat into energy. Exercise during this time, you will consume 30% more fat. The metabolic rate of strenuous exercise is 20 times that of static exercise. Grasp this exercise time, add a 30-second accelerated run every 5 minutes in long-distance running, or add 1 minute climbing in the process of cycling exercise, and you can get ideal fitness effects.