Hello, 13 years old is in a critical period of physical growth and development. It is recommended not to drink oolong tea to lose weight. Diet tea contains more or less harmful substances, which has certain influence on growth and development. It is suggested to control diet reasonably, formulate healthy eating rules, eat less fried food and eat more fruits and vegetables. Reduce the intake of high-calorie food, try to eat lightly and control appetite. In addition, you can download some videos of yoga and aerobics from the internet, and you can practice more at home at ordinary times, which is very helpful for shaping your body.