12 years old children lose weight mainly by controlling diet and increasing exercise. Drugs are not recommended to help children lose weight. This has little positive effect on children and great side effects. It is not recommended to use drugs to lose weight. For children, the specific ways to lose weight are as follows:

First, control children's diet. Children are still in the process of growth and development, so we can't reduce the nutrition supply too much. Therefore, it is suggested to provide children with some low-carbohydrate low-fat but high-protein recipes, which will help them lose weight. At the same time, children can eat more, such as high dietary fiber content, strong satiety, low energy, fresh vegetables, fruits and so on. Help children lose weight.

Second, simple diet control is definitely not enough to lose weight, and it needs to cooperate with exercise, but it is best not to let children do particularly strenuous exercise, otherwise children may have a big appetite after exercise, but will eat more. It is suggested that children do some easy-to-stick, slow and not particularly strenuous exercises, such as jogging and aerobics, which will help children lose weight.