Why do most girls think they are fat when they are very healthy?

They want to see if you love them no matter how they look.

It depends. It can sometimes be a mental health issue, driven by society. In other ways women naturally have more fat than men because if they carry a child then they need that fat. Therefore, women feel like they need to have less fat than men in order to be healthy, even though they aren't engineered like that. 

I hoped this helped, though I'm not sure how accurate this is!

Little kids are eat dirt all the time so im sure you are fine

Well i guess u know a lot of that, huh? that's nasty of me, isn't it? lol