07 May Scooby-Doo: The horrors of being a size 8
A direct-to-video release called Scooby-Doo! Frankencreepy finds the Mystery Machine gang in their natural habitat: a spooky old castle inhabited by a nefarious villain. When Daphne has a run-in with said villain, he hexes her with a curse that causes her to grow from a size 2 to a size 8—a size that’s still smaller than that of the average American woman.
When the Huffington Post asked Warner Brothers to comment on the insulting choice of curse, Warner Brothers stated that they believe the message is actually a positive one.
Although you are correct that Daphne becomes bigger in the course of the story, the message is actually a much more positive one. The plot of the movie involves the Scooby gang becoming cursed and losing what means the most to each of them. Fred loses the Mystery Machine, Shaggy and Scooby lose their appetites, etc. Daphne loses her good looks (mainly her figure and her hair). While Daphne is at first upset by the sudden change, there is a touching moment where Fred points out that he didn’t even notice a change and that she always looks great to him. At the end, when Velma explains how they figured out the mystery, she points out that the curse actually DIDN’T take away what means the most to each of them: their friendship. The loss of Daphne’s regular appearance is proven to be a superficial thing, and not what actually matters the most to her.