Bicycles, of course. My legs became smaller after riding a bike. The most important thing is that you should control your diet

Eat less greasy and salty food! ! Otherwise, it's useless for you to exercise more.

As for the rebound, it's up to you. Can big fish and big meat not get fat every day?

This is to pay attention to diet and exercise for more than half an hour every day. I believe it should not rebound too fast!

Still a word: exercise is expensive, I hope you succeed!