This is based on science. First of all, if you learn to dance, you should do all kinds of movements very standard, such as folding or folding or other movements, especially some movements in ballet. You often do muscles that can exercise your waist and legs, as well as muscles all over your body. When muscles are tight, the quality will be improved, and the quality of muscles will also be improved. Of course, the waist will be thinner. Why go back? It's because the mass of muscles has improved and the volume has become smaller. You will look slimmer when you get smaller, and your explosive power, endurance, immune system and other functions will be enhanced to some extent.