i never realised covering your chest is bad body language I always cover my chest feeling gains from working out but I am trying to get out of the habit, I just do it sub-consciously but I must make more of an effort in future if it portrays defensive body language.
One of the points Navarro makes in the book is that no single action means anything, stuff is only significant if the person doing it wouldn't normally do it. If your habit is to cover your chest then it doesn't mean anything. That said, someone would have to know your habits to know it was normal.
Navarro is an ex-cop and interrogator so he's looking at body language from that point of view. His theory is that there are parts of the body that are physically vulnerable, the chest, the abdomen, the neck, the inside of the arms where the blood vessels and tendons are, etc. He says when people are under stress they naturally try to protect these areas. When they are comfortable they expose them. Interestingly he says the most serious is the inner arms and people who make a big effort to hide that part of their bodies often have had really bad shit happen to them.
Brilliant book, great for watching how women are behaving and he's been pretty much bang on in my experience.