If you are not too fat, you can do abdominal training to lose weight, but as you said, if your stomach is big, it is estimated that you can't lose weight. You just need to start losing weight all over your body, and you can get your stomach back. After all, your body can't be belly-down, and other places are still fat, which is definitely unscientific, so only when you are all thin, other places will be thin.

You can do anaerobic exercise (muscle strength training) combined with aerobic exercise every day, and losing 20 pounds is a trivial matter.