Hi soulsnette, welcome and glad to see you! Yes, keeping it off is the bottom line of fat loss. The great majority of fat losers have done the diet thing only to gain it all back and more. The reason being is, they didn't change the mind, they still love those dangerous and unhealthy foods, in fact, they can't wait to stop the diet.
To keep it off for good requires a total commitment to a change in lifestyle, you have to realize first of all why bad food is bad, the damage it does to the body. Your young, now's a good time to start.
Anyway, look around the forums, hopefully you'll find what works for you.
knotty