Obviously, fitness can lose weight, and it must come from sweating. If you sweat, your whole body will get hot, sweat and clothes will stick to your body, and it will be very uncomfortable.

Then there is the difference between men and women. A man's upper body has no sex organs, so it can be exposed. At this time, many men will choose to take off their shirts. Women will wear sports vests, which are also cool and can protect privacy.

So that's why so many people in the gym don't wear shirts. It usually only happens to men. Oh, it would be weird if it was a woman.