I've been reading some contradictory things in regards to finding out if your hair is healthy or not.

I read somewhere that healthy hair will stretch to double it's length. But here, I read that if your hair is stretchy, it's lacking protien?

Are there any articles here that I can read up on in regards to findin out if your hair is healthy? I read that you can take a strand of hair and see if it sinks/floats in a cup of water. Again, one article said if it floats, it's healthy but if it floats, it's not healthy.

Just ever so curious! Thanks!