You know, my first reaction to Lady Gaga's weight gain was to wonder if it were a real weight gain or some kind of performance art through which she wanted to make a statement about something, like how people judge by appearances etc. I don't mean that as a criticism of her either. It's simply that she does use her appearance to make various kinds of statements, even when she's not on stage. I don't think I've ever seen a photo of her in even an airport, for instance, when she wasn't wearing something that wasn't meant to be more than just an outfit. I could even see her opting to go ahead and go off a stringent diet--if she were on one in the first place; I have no idea--as a statement that she shouldn't have to be on one, that people are too quick to judge celebrities (especially female celebrities) if they gain weight for whatever reason, or something like that.
It's probably something much simpler than that, but because of who she is and the kinds of choices she's made in the past--the meat dress, her male alter ego, arriving at an awards show in a giant egg/womb--it was hard for me not to go there immediately. She knows she's on a stage/platform wherever she is, and she uses that as opposed to avoiding it or shunning it as some celebrities have.