Your body is still developing and you must focus on eating healthy as adolescence is a critical growth period. If you are a girl, then are you having regular periods? If yes, then there is no reason to worry. Don't bother about what people have to say. Focus on being healthy and fit more than having an attractive body shape. It is absolutely fine if you have a high metabolic rate. It only suggests that you need more energy as your body burns calories efficiently. So eat well and stay active. Don't get stressed about your appearance. Metabolism slows down as people age so maybe that will happen to you too once you reach your 30s. Once metabolism slows down, people gain weight no matter how little they eat and then worry about losing weight! So why do you worry?