I don't eat very much at school because I think am very fat I go on wii fit and just dance 2 but it doesn't help :(

No, you're not fat, plus your body will change tremendously during the next five years. Eat at school, or you will hurt your body and you won't grow right.

OK thanks but I think I still could do with losing about 2 stone

TWO STONE?? You'd be nothing but skin and bones!

Do you want me to tell you what awful damage you will be doing to your muscles and nerve cells and organs if you lose weight? (Right now while you're growing and maturing, your body NEEDS good food put into it, so your engine, your body, will run well.)

I know but every one else in the year is skinner than me except a girl who is 18 stone and 13 and a couple other people

You're going to live your life comparing yourself to everyone else and try to be like everyone else? How sad.

And what's funny -- some of them are looking at you and thinking, "I wish I could look like her and be like her."

no am not comparing my self to anyone.. well mabey just a bit but i am a bit over weight and i a not conftable with my body coz i am ashemed of it
Leave your weight alone, and in six months (if you eat good and proper foods), you will be a bit taller and your shape will have changed all by itself. This will happen until you're around 18.

Now, tell me what's REALLY wrong, what you're REALLY uncomfortable about. It's not your weight, is it.

You are only 13 years old. You have plenty of time to grow more in height and everything will equal out when you get older. Weighing what you weigh now is completely normal. Nobody wants to be skin and bones.