It's easy for boys to lose weight.
Abdominal muscles do sit-ups and fly back.
Do push-ups on your chest muscles.
The legs are so big that they are simply push-ups.
If you want to thin your legs, go jogging. Jogging below 30 is recommended for more than 25 minutes. It depends on your endurance. If you really can't hold on, go from less to more step by step.
Remember to pull the corresponding ligament after running practice.