Hi Elsie,
I'm new here as well, but not to this type of venue. Welcome to the boards. I was wishing there had been something like this when I was your age. You will find people here of all ages all over the world that have stories, suggestions, questions and inspiration to share, all for the asking. Just speak up, someone will be out there to answer you. There are areas specifically for younger people, special diets, lifestyles, you name it, but i'm sure no matter where you post someone will help.
While i'm old enough to be your mother
I still remember being in highschool and feeling like I had to fast for days on end or be in every activity till I was going to drop. More than anything, I found, like many others it was the cycle of dieting and regaining the weight that got us where we are. Hopefully, you will be spared the "roller coaster".
A balance is key. Weight loss is the "side effect" of healthy living. Some have found that certain foods are a bother to their system like sugar or flour. You can do some experimenting on your own to see if these bother you. Otherwise, what ever you choose to do, make sure you can do it for the long haul as a lifestyle not a "diet". Little changes do wonders. Increase walking distance, take the stairs instead of the elevator, go dancing more, ride a bike, some weight training is good, it's a fact that more muscle means more calories burned, eat more fish and whole vegtables, drink more pure water, eat less fast/junk food, don't obsess over the scale. Just my 2 cents...
Have a great time here!
Karen