I get hungry every 2-3 hours without fail?

Maybe your getting your period? Maybe your growing? Or sometimes, it is totally natural and normal people go through periods where for some reason they get hungry more often- no reason at all for it. It could also be that maybe your not eating enough at your meals when you do eat. How tall are you? Assuming your like an average height (5"5) 17 year old female- you should be eating close to 2300 calories a day. A normal day should look something like this

Breakfast:

a medium bowl of cornflakes w/ strawberries, milk and a cup of juice

Snack:

peanut butter w/ banana

Lunch:

tuna sandwich w/ lettuce & tomato, baby carrot sticks, snack bag of pretzels, lemonade

Snack:

handful of cherries and balance bar

Dinner:

mashed potatoes, medium piece of turkey, string beans, dinner roll w/ butter

Snack:

yogurt w/ 2 granola bars

if you are eating small meals (about the size of your fist) that have mostly carbs (like veggies/rice) and very little protein (meat/chicken/fish), that could be one of the reasons why you get so hungry 2-3 hours later. youre not eating enough calories. try eating a full meal with 40% protein 30% carbs and 30% fat (about 700 calories) and see what happens. if you are still starving 2-3 hours later, you should see a doctor. excessive hunger (and thirst) is an indicator of diabetes. if you are very skinny and can't gain weight no matter how much you eat, that can be an indicator of an overactive thyroid. either way you should see a doctor and have him do some blood work on you. better to be safe than sorry.

That was what was naturally meant to be. Short meals with little breaks instead of a sit down four course meal. It may be the vitamins. Keep up your high activity level and go for a lot of nutrition. Even if you stop the vitamins try to make this cycle your routine.

It's normal - those big meals probably aren't as big as you think they are. Eat when you are hungry. The vitamins may be helping you metabolize food faster too.

Nothing to worry about. If you can, add more whole grain foods to your meals. Get rid of simple carbs and eat more complex carbs. You will stay full longer.