Start with making some adjustment in food of your child, and it possibly can serve in helping you control their weight. For example, cut the number of sugar-made products/sweets and some other such changes. However, make sure you keep in mind the dietary needs of your child and do not make any major cuts in their food.
Sometimes children look heavier or overweight because they are not active physically and as they grow up and become physically more active, they start adjusting their weight according to their age and body requirements gradually. So be patient and let your child lose some weight on his own after they become active. Being healthy can help quicker and healthier growth of body of your child. So do not worry too much about the weight of your child.
If you are really worried about the weight of your child and cannot find any other method working for the weight loss, discuss this issue with a doctor. A pediatric might be able to help you recommend some changes in the child food or some little supporting exercises for your child that reduce their weight quickly. Even the doctor will not recommend you the option of surgery straightaway. So do as the doctor tells you to see if it helps.
After having used all other options with nothing much achieved, you can discuss the option of surgery with your doctor. Share all the information with your doctor, including the options that you have been trying to help your child lose weight, unsuccessfully. Also make sure you give the doctor information about any physical changes you have witnessed since you have been trying other methods for helping your child lose weight. The doctor only will be able to help in giving a nod for a surgery if they know as much about your child as you do. It is also essential for the sake of health of your child that you let the doctor know all the details before committing to surgery.
You as a parent also have a right know if there are some side effects or any other implications of surgery on your child. Make sure you know all this before evaluating the option of surgery for your child. Since your child is unable to understand these things, it is your duty as a parent to know welfare aspect of your child before you let them go under the knife.