This is total crap. I pretty much always have abs and my body fat percentage has been all over the place. I had no abs when I was around 18% body fat because I had an eating disorder and my body was eating my muscle to survive.
This stuff depends on the persons individual body type and spreading shit like this as fact is a good way to help promote eating disorders and fixations on numbers instead of health.
I am mad now. But seriously. Stop making up facts Tumblr.