Even if you do 1000 crunches everyday, you’d trim the fat around your belly as crunches tone the muscles that lie underneath your fat, but do very little to help you lose weight.
Crunches will have almost no effect on fat loss. It is not possible to lose fat only from a specific part of the body of your choice. In general, where it stores fat first is where it will lose it last and vise versa.
Any exercise will burn calories but no exercise will burn fat unless your diet allows it. You can burn fat in your sleep or you can run all day and never burn any fat. It all depends on your diet.