Drastic changes are much harder to stick with than small changes. Try reducing the size of the portions you eat and giving up regular soda for a week. Once you have that down, start gradually introducing healthier foods and exercise into your life. Slowing down can help because it takes about 20 minutes for your brain to recognize how much is in your stomach. Sometimes taking a break before going for seconds can keep you from eating them.
Many teens find it's helpful to keep a diary of what they eat and when.
Reviewing their diary later can help them identify the emotions they have when they overeat or whether they have unhealthy habits. A registered dietitian can give you pointers on how to do this. Many people find that eating a couple of small snacks throughout the day helps them to make healthy choices at meals. Adding healthy snacks to your three squares and eating smaller portions when you sit down to dinner can help you to cut calories without feeling deprived. Five a day keeps the pounds away.