If you're 6'00", then you really don't want to be 125lb. 5'00" girls can pull it off. You didn't say what gender you are, but whether you're male or female, at your height you want to be more than 125lb. If you're a girl then I wouldn't recommend going any lower than 150lb, and depending on your frame you might need to be at least 160, 170 or even 180lb. If you're a boy, then at 6'00" you probably shouldn't be any lighter than 180lb, and even your current bodyweight could be quite preferable, although you'd probably want a different body composition.
Of course, saying all this, you exhibit signs of body dysmorphia in the fact that you thought starving yourself is a good idea and that you think you need to be at such a ridiculously light weight. I think a mental health specialist is probably more important to you than a diet or exercise program, but if you're going to do anything fitness related, read the stickies right here in the young athlete development section.