Answer:
I think that doing only crunches in not an effective way to lose belly fat. You need to balance the body, meaning that if you do crunches you would have to do another type of exercise to even it out. There could be side effects from only working one part of the body, and it might even take longer to lose the weight fully. Doing a full exercise routine is the faster, easier way to increase muscles and lose weight.
Ani_H.
[Do not plagiarize] ありがとうございます (thank you) \( ^_^)/