should the belly poke out when you sing?

I recently got a question from a student who was taking my '3 Step Prep System for Voice' online course.  

She asked: "When I engage (the diaphragm) I feel like my belly is poking out.  Is this what I should feel?"

My answer was this:  
"Rather than the feeling of 'poking out', I like to think of the feeling of EXPANSION.  Your belly should be relaxed, the diaphragm area firm, and as the diaphragm engages, it  EXPANDS​ slightly down and out.  If you feel that you are 'pushing' your belly or diaphragm area out, then back off a bit because you don't want to create any tension in your body.  Think of the simple act of 'filling up with air' as a natural and dynamic basis for proper breathing."  Cheers, Beth Lawrence