I've been in this situation myself. I can't lose weight when I exercise, and the abdominal ripper has no effect on me.
The point is, I was fat. When I was fat, my meat was loose, so my skin was already tight.
Just like when you are pregnant, your stomach will become bigger, and your original muscles will be deformed, not to mention that your stomach has long lost its original tissue.
Then when you lose weight, the other skin of your body is intact, but it can be tightened by your exercise, and the loose meat will become muscle. However, the muscles in the stomach have been destroyed. If you don't use professional skin care products, it seems difficult to return to the prenatal state.