SG isn't fat. She's definitely big, but in a very unreal way. Her belly is flat, and though her tits are huge they are not saggy at all. Ororo has way saggier tits than SG, so does Emma.
For those saying SG is the first thic figure, take a good look at Emma and Ororo. Oni was already playing around with the "flat-bellied but thic chicks" he clearly just lost his touch over time. Emma is amazing, but Ororo is already a little weird, Doreen just got weirder.
But if we think about it in a logic way, all x-girls should be fit or athletic, as they are constantly training for combat. It might be my Asperger's speaking, but I don't see it as body shaming or body depreciation, but simple logic and common sense.
For instance, I love the fact that Kitty is petite, and I would love to have more petite girls. But I wouldn't feel bad if she were fit and defined like Laura or Jean, though fit/athletic girls are not my thing.