How thin is too thin?

So I haven't blogged in awhile but something caught my attention and pulled at my emotions. I have a tumblr and one girl I follow is trying to lose weight. I haven't paid much attention to her blog until now. Today I decided to read some of her entries and it just shocked me. She is on a diet of less than 300 calories per day and fasting. Then I went on to look at some her followers and they are all starving girls who still think they are fat and gross. When is enough enough? As I was reading these blogs I found myself feeling scared for these girls and scared of the road an obsession to lose weight can pull people down. I have struggled with my weight and I have had more "fat days" then good days. But seeing how these girls (my age and younger) have let food completely consumed them just tore me apart a little. It's sad. So I say to them and those with the same struggle: If you are overweight and not happy with your body, PLEASE lose the weight in a healthy manner. Don't reduce yourself to nothing because you may feel like nothing. You are beautiful no matter what size you are. And no matter how thin you are, you will never be beautiful unless YOU think you're beautiful. Don't starve yourself to nothing. What are you proving? That you didn't know how to take care of your body when you were obese and you STILL don't know how to care for yourself? Please. Beauty comes from the mind. You are beautiful. Eating a cheeseburger won't change that.