Harvey Fierstein is 6' 2" and weighs about 250 as he plays the 300 pound Edna Turnblad.
You can put any actor in a padded suit, but the actor needs to start with a round face and sufficient stature for the role. I'm sure there are minimum height requirements for Edna versus the shorter Tracy.
Robin Williams has a thin face.
Nathan Lane is short, I think.
John Goodman would probably be the right size for the role.
Although I understand that a woman COULD play the role, casting a man adds a different dimension to the part as well as providing a great acting opportunity.
Ray is the author of the Brad Frame mystery series, and two suspense novels. He is also the author of a one man play based on Ben Franklin. http://www.rayflynt.com