My daughter reads too much?

I think my daughter is reading too much. All she really enjoys doing is reading her books. Last year she read close to 250 books. She reads for at least 4 hours a day, even after she's done with homework. She usually rushes through her homework to get to pleasure books. She usually falls asleep with her Kindle in her hands. She spends most of Saturday laying on the sofa in a t-shirt and panties reading books. She usually reads for 5 or 6 hours each on Saturday and Sunday. She never leaves her Kindle at home, she reads during car rides and during her free periods at school. She only has two friends (both girls) and they usually just talk about books together and sit together and read during free periods. When her friends come over all they do is sit around eating pastries, drinking tea and talking about books like a group of old ladies. Those three girls are her only friends, I've never seen her associate with a boy or even go to a party even though she's 16. I've asked her and she told me that she isn't depressed or using books for escape, she just loves reading. This doesn't seem normal to me, though. She likes to do nothing else. We've tried making her go outside when it's nice out, but she usually just sneaks her Kindle out with her and reads. She plays no sports and doesn't exercise, she says she hates exercise. I'm worried about her health (she's a healthy weight, but she needs to exercise) as well as the fact that she does nothing but read books. What do I do about her?

Read more: My daughter reads too much?