Well, women more than men have been subjected to weight shaming. I agree that there are role's which require a certain body type, but Carrie is not a young woman and I think Spanks would have worked just fine.
Jason Mamoa is a young man and can recover from excessive weight loss/gain. Christian Bale did it for The Machinist, Chris Hemsworth for the current Moby Dick movie. I believe Charlise Theron did it for Monster. But they were all much younger than Carrie.
*New thread?