At your age, when you're still growing, the best thing is to combine exercising with cutting out processed foods. Find an exercise you like: running, dancing (real dancing, not a class where you stand around half the class period), gymnastics, cycling, something that keeps you in constant motion.

Then, take a look at what you're eating. If you're eating Fruity or Sugar or Golden anything, switch to something like eggs some other protein breakfast. Several studies have shown that eating a good dose of protein for breakfast makes you less hungry the rest of the day.

For snacks, eat things like carrots, pepper strips, cheese, or nuts. Cut out chips and crackers.

For your meals, stick with meat, vegetables, salads, and some fruit. Cut out all sodas, unless it's something like Zevia. Unsweetened iced tea comes in all kinds of flavors and is a great choice, but you should have some milk (again, you might not be through growing). Sweeten things with a natural sweetener like Truvia or its derivative stevia, but it's even better just to get rid of your sweet tooth. If you don't eat any sugar for a week and then have some strawberries, you'll think your tastebuds have died and gone to heaven!

Don't cut out all fats, though. Lowfat has been pretty well debunked as a diet strategy in the science. Fat helps you feel more full, so again, you end up eating less, with fewer calories. Plus natural fats often contain vitamins or have other beneficial qualities, like pasture-fed butter having vitamin K3, which is not widely available; or coconut oil having potent anti-microbial properties.

Good luck! Use a Seinfeldian chain each for your exercise and for your eating habits, and don't break the chain!

http://smarterfitter.com/chain

First off... how you talk to yourself is paramount. You are NOT a loser! So... why would you want to "lose weight"? Your unconscious knows you aren't a loser, so it won't want to "lose weight".

Secondly... what would happen if you lost a ring? You'd go look for it, right? So, what do you think your unconscious is doing when you lose weight? You go looking for it! (There it is! Right over there!).

So... tell yourself that you'll LET GO of your weight. (You let go many times a day, right?) And... I NEVER diet. Who wants to do anything where the first three letters are DIE?

Now... Off to the weight management part:

It's a simple equation: Calories in - Calories out = weight change. So, very simply: what you eat (the TRUE definition of "diet") and exercise.

Eat healthy, balance your exercise... and your body will be just fine.