The so-called slimming is actually to lose excess fat and keep the body's fat ratio at a very low level. The effective method is long-term aerobic exercise, with no less than 45 minutes each time. For example, jogging, not less than 45 minutes at a time, can not stop halfway.
Just look at the long-distance runners. They are not thin, even their thighs are not thick every day, because they have done a lot of aerobic exercise for a long time. Not less than 45 minutes at a time because, generally speaking, it takes more than half an hour to exercise before you really start to consume fat, and even the muscles start to consume after 45 minutes. This is why athletes who specialize in fitness will do aerobic exercise to reduce fat, but they will not do aerobic exercise for a long time, because it will consume their hard-earned muscles in vain.
Generally speaking, if you just lose fat, it is enough to run for 30-45 minutes every day. In fact, after reducing the body fat rate, your arms will naturally become thinner, and few people will specifically lose muscles. If your arms still feel thick after reducing fat to a very low level, it should be a personal bone problem. Some people have thick bones, while others have thin bones and are born with them. To be honest, I don't think playing badminton will be rude. If the arm muscles were so easy to practice, bodybuilders wouldn't have to work so hard.
In a word, I suggest you run long distances every morning.