Give you a recipe and some suggestions ~ (oatmeal diet)
Breakfast: Drink a large glass of warm water after getting up, swallow it, then do some stretching exercises to promote gastrointestinal movement, and then eat a banana and a bowl of oatmeal. You can add some honey if you don't like it.
Lunch: oatmeal with vegetables (preferably with less salt)
Dinner: yogurt and boiled eggs (you are a junior high school student and still in the development stage, so pay attention to nutrition)
Eat some fruit when you are hungry, but don't eat after 8 pm.
Be sure to exercise before going to bed, do 50 sit-ups and ride an air bike for a while. You can order some aerobic exercise according to where you are fatter, but you must exercise for more than 40 minutes.
This is how I lose weight. I weigh 20 A Jin months. I hope you stick to it!
Any method is a good one as long as you can persist.