Normal, no need to adjust. Before menstruation, abdominal fat thickens to prepare for pregnancy. Once pregnant, it will protect the uterus. After menstruation, there is no pregnancy and no need for protection, and the abdominal fat layer will become thinner. This is the instinct of the body to adjust itself, don't worry.

This situation also shows that the secretion of estrogen and progesterone in your body is particularly normal, which is a good thing.