Eat on a small plate and cut your eating way down. Drink water before meals because it fills you up. If you are not hungry - don't eat. There is nothing wrong with fasting for a few days, but drink plenty of water while fasting. Eat good vegetables, broccoli, zuchinni squash, cauliflower, mustard greens, kale. Eat a boiled egg with toast for breakfast. Half a sandwich for lunch no chips and drink water. Small portions on a small plate for dinner. Fruit for snacks - apples, oranges, grapes, kiwi, - Cantelope and watermelon are good also. My policy is if you are hungry eat a little more - if you are not hungry don't eat or eat less. Don't use artificial sweeteners in anything. Nothing artificial is good for you - absolutely nothing. If you must have a candy ever so often eat a peppermint or even a butterscotch because they last longer while melting in your mouth. You can do it. At 14 you should lose 20 lbs or more the first month.