I haven't heard that you can gain weight, but losing weight is true, as long as you can stand it. Generally speaking, if you actively run after a badminton match, you will get about 1 km. The strongest players are the top players in the world, such as Dānlín versus Li Zongwei, who have to run at least 6 kilometers after a race. So big badminton can burn calories and achieve the effect of losing weight. Of course, you have to persevere and keep playing. Good luck!