As a teenager, you go through many changes. For one thing, your body is on its way to becoming its adult size. Along with these changes, you are probably becoming more independent and making more of your own choices. Some of the biggest choices you face are about your health. Why? Because healthy habits, including eating nutritiously and being physically active, can help you feel good, look good and do your best in school, work or sports. They might also prevent diabetes, high blood pressure, heart disease, osteoporosis, stroke and some cancers when you are older.
MedlinePlus - Teen Health