How to maintain a healthy eating style?

Hey! I had the same problem once. It's really important that you eat every few hours, not only to keep your energy level up since you're very active, but also because you're so young and your body needs the nutrients to fuel your growth! Speaking of nutrients, another reason you probably crash is because you're eating foods that are heavily processed (for example, pop tarts). Try and find some healthier options that are more natural. Usually I eat oatmeal in the morning with some cut up fruit, I usually snack on fruit or nuts or an energy bar (Larabar) between breakfast and lunch. Lunch is usally brown rice and veggies. Dinner is usually a huge salad with chicken or salmon. If I'm hungry afterwards, I usually either go for fruit, egg whites, a bowl of cereal, etc. This usally satisfies me and keeps my energy high throughout the day! So, my suggestion to you is to find more natural foods that give you energy. Good luck!