What is wrong with me feeling tired all of the time?

Teens need more sleep than any other age group, however, if you are having trouble getting through the day without a nap, perhaps have a good close look at your lifestyle. First, have a good check up with your doctor (blood tests etc) to exclude any underlying problem and reassure you. If you are ok medically, then try this: with my teens, we have the 95% rule!! I stuff them full of veges and fruit, and healthy but yummy low fat meals etc 95% of the time, and then they can pig out the other 5% of the time with their "junk food fixes" ie McDonalds, pizza etc. They are happy with that, and really enjoy the "healthy stuff". Another really important thing is to MOVE MOVE MOVE. The more you move and exercise, the more energy you get. (And it's really mood enhancing) Do nothing and you will quickly become sluggish and tired. Do the MOVE to things you really enjoy, like dancing, walking/running the dog, skate boarding, swimming etc etc. Hope you feel better soon, and this helps a little.