Hello! Thank you for writing! Do you have any other sign except not capable of losing weight? You can check your thyroids. I think that you should better visit a clinical nutritionist. Don't starve yourself because you are growing up and you need a lot of different nutrients for this. I will give you general tips but the best is to have a personalised diet by a nutritionist. Eat a lot of fruits and vegetables. Eat : milk, yogurt, fish, chicken, eggs, dry fruits, nuts, different kind of seeds: chia seeds,etc. Dint consume fried foods, fast foods. Try to eat at the same time everyday. Exercise every day. And don't try starving because after that you will eat double and also doesn't help you through growing. Eat frequently and few qualitative foods. Portion, what you eat and when you eat are crucial.
Thank you. Best regards.