It's called traction alopecia:I once saw an article about a ballerina talking about how she was losing her hair because she kept it in a tight bun so often. So dirt, hormones, and dying follicles -- seems like a recipe for thin hair. But, don't dainty gorls have thin hair?
A good example of this is Jojo Siwa:Traction alopecia is hair loss that’s caused by repeatedly pulling on your hair. You can develop this condition if you often wear your hair in a tight ponytail, bun, or braids, especially if you use chemicals or heat on your hair.
Traction alopecia can be reversed if you stop pulling your hair back. But if you don’t intervene soon enough, the hair loss may be permanent.