My personal opinion is don’t do it. You are young and recognize you have a weight problem- which is awesome. I would ask your parents about going to see a dietician to get some sound advice. If you do decide to fast, don’t do it on two consecutive days- it is extremely hard and will be miserable. In short- it won’t last and you will binge. Also- I can understand you don’t like excercising but try to incorporate a 30 minute walk into your schedule each day. It doesn’t seem like much but it will help. Good luck!