"... his body language", say researchers from the University of Aberdeen.

Here is the article: http://medicalxpress.com/news/2016-11-lois-lane-clark-kent-superman.html

Good reasonable article, but that's why Clark bends over and walks like a normal man where Superman strides confidently when he isn't flying.
In the new Supergirl, Kara acts differently by acting shy around her bosses or those not in the know. With her friends she acts more confidently.
r/
Artemis

I noticed that... but apart from suspension of disbelief, I always thought Lois should have found out much sooner...