Dude, you're wrong. You can't lose weight by fitness. Fitness exercise muscles are anaerobic exercise. Anaerobic exercise does not lose weight, but exercises muscles. So after you exercise, the muscles in your chest and buttocks will increase a lot, which will naturally become bigger. But if you feel it, it's hard inside, not fat, but muscle.

If you want to lose weight, you should do aerobic exercise, such as running instead of swimming. Only aerobic exercise can lose weight.

I suggest you do aerobic exercise first, and then start to exercise your muscles when you lose some weight, and at the same time keep an appropriate amount of aerobic exercise, so that you can shape your body, not only thin, but also slim!