James, in the past year and a half I've lost more weight than you currently weigh. You should check http://www.nhlbisupport.com/bmi/
and find out what your correct BMI (Body Mass Index) should be and stay within that range. Even if you don't need to actually lose weight right now, you are still growing and should establish good habits now.
It can be done but it is effort. You're exercising -- that's great! But that's only a part of the equation.
David has one idea: weights. Muscle weighs more than fat but it also burns more calories than fat. You should add strength training (always get a doctor's okay before you start or significantly change any exercise program
), generally every other day is good. This is to give your body a chance to recover. So do, let's say, four days/week. Monday, Wednesday, Friday, Sunday, Tuesday, Thursday, Saturday, then back to Monday. Two days (alternates) should be devoted to core. That is, back, glutes and abs. Then one of the days is upper body (biceps, triceps, chest, shoulders) and the other is lower (quads, hamstrings, calves).
Hence you could do as follows for a strength training program
Monday: biceps, triceps, chest, shoulders
Wednesday: back, glutes and abs
Friday: quads, hamstrings, calves
Sunday: back, glutes and abs
Tuesday: biceps, triceps, chest, shoulders
Thursday: back, glutes and abs
Saturday: quads, hamstrings, calves
Then just start over again. This is 3 sets of 15 reps for 2 types of exercise per body part. For the lower body, for example, you could do crunches from 2 different angles, squats, lunges and both standing and seated calf raises. Start small, with, say, 5 lbs. of weight and work your way up. You want to work it so that the weight is the most you can do this many reps and sets and still maintain perfect form, and be totally exhausted when you're done. I assure this will not take forever! I do my program in about 15 - 20 minutes in any given morning. You really don't want to take more than maybe a half an hour doing this. It is, by the way, in addition to the cardio you're currently getting, and no substitute for it.
Get yourself a set of resistance bands or a stability ball (or both!) and use them in conjunction with your weight training. These allow for different movements -- sustained long-term weight loss is dependent upon variety so you need to switch things up, and these two items help you to do just that. Try your weight training while sitting on the resistance ball instead of a bench or chair, for example.
3500 calories = 1 lb. It's that simple, but also complex. You need protein to build muscle, but you need carbs for energy so you can work out at all. And you need fat to help you feel full but also to assist with other functions, e. g. gastro-intestinal stuff, among other things. But junk food is not the way to get any of that stuff, not even fat.
What you want is a balance, about 40% of your calories from carbs, 30% from protein and the remaining 30% from fat. The fat should be divided more or less evenly among saturated (like from meats), unsaturated (like from vegetables) and monounsaturated (like from olive oil or nuts). There is no place in a healthy diet for trans fats, which are abundant in junk food. They are very bad for you.
Another thing -- which butrflynet mentioned -- is there's a lot of sugar in what you're eating. Eat less sugar and you may find yourself eating less of everything. This is because sugar provides a rush and then a letdown -- and it's the letdown that can trigger some people into overeating.
A few quick fixes for diet:
1) Swap soda (even diet!) for skim milk, water or fruit juice. Fruit juice is the least desirable of these three but it's better than soda. Make sure the main ingredient is fruit and not sugar.
2) Drink 8 - 10 eight ounce glasses of water per day. Try 1 or 2 of these before every meal. You will eat less, and your body will metabolize everything better. Also try water (you can put a little diet flavoring in it; companies like Crystal Light and 4C make flavor sticks) when you are craving a snack. You may be thirsty rather than hungry -- many of us confuse these signals.
3) Even if you're not much of a cook (or the people you live with aren't; I realize you're a teenager), making sandwiches or omelets is pretty low-key, easy stuff. Instead of a takeaway, get yourself a pound of turkey breast from the deli, salad fixings and a loaf of whole wheat bread and mustard (I'm partial to dijon myself). So instead of takeaway for a week, eat turkey sandwiches with lettuce and tomato on them, and have a piece of fruit on the side. Keep in mind that deli turkey is going to have salt, but you'll still be doing better than McDonald's or the like. Plus this will get you into a habit of making food for yourself. For the next week, try something else, like ham or maybe throw the turkey into a salad or an omelet (try different vegetables, like mushrooms and onions for this) instead of on a sandwich.
4) Good dietary habits are all about making choices. I am not going to suggest recording your food (even though it's a very effective thing to do) because you're a teen. But you can make good decisions all the time, every time. For example, between food that's fried versus grilled, pick grilled. Between a tomato sauce and a creamy one, pick the tomato-based sauce. Between salad and soup, either is fine so long as the soup isn't cream-based. Between white bread and wheat, pick wheat (or rye or pumpernickel, if they are available and you prefer them -- they are also, generally, a wholer grain). Between meat and vegetables, both are fine so long as the vegetables' mass is about twice what the meat's is. Between steak and fish, pick fish, so long as it isn't fried.
5) Eat breakfast! I cannot stress this enough.
6) Eat every few hours. Keep the tank about 1/4 - 3/4 full or so. Don't get too starving and don't overstuff yourself. The bottom line is, if you are overstuffing you are probably overeating, and if you are starving you are setting yourself up for just eating the first thing, rather than making informed choices.
7) Less TV, less video games, less computer. Yeah, I know, I sound like a parent. But sedentary life not only keeps you from exercising, it can also set you up for a lot of mindless snacking. Yes, you should eat frequently, but that doesn't mean you should eat constantly.
Let me know if there's any other ways I can help you. You can do this.