I started out this post with a list with fat male characters, to show how fat is accepted when it comes to male characters, but not when it comes to female characters. Like Bulkhead, from Transformers.
But there's a deeper thing here that I disagree with, namely that Glimmer is fat. She's not a supermodel size, or a fit warrior like Adora, but she's not fat. At best, she may appear that way in contrast with the other characters. And, yeah, to a point I would agree that American fat acceptance is ridiculous, and unhealthy. But Glimmer is not an example of this. Glimmer is not obese. Her shape is that of many girls and women, who are perfectly healthy specimen of human forms. Hers is to show that being a girl comes in many forms, just as many as guys have. So there is a double standard there, if you think Glimmer is fat, where a guy with the same general build, say Eddy from Ed, Edd, and Eddy, isn't. Neither of them are, but if you think Glimmer is fat while Eddy isn't, then you're holding women to a much higher standard than men. And, yeah,. that IS problematic.