Sister thinks your round face may have something to do with being overweight, so don't deliberately lose weight. Because now is the time for you to grow up, you will be malnourished and afraid of delaying your normal development and growth. You can have three meals a day as usual, don't eat anything after 7 pm, and do more exercise, so that you can be healthy and beautiful. Spend all your time studying, and gradually you won't care about your little face. I hope your sister's suggestion will be adopted.