This sounds like my aunt and cousin. Anytime my aunt sees me or my sister she says some crap about we need to give her whatever outfit we happen to have on because we gained weight and can't fit it anymore. The thing is, she's bigger than both of us (she just doesn't have the T&A).
My cousin would do this when we were younger. I wasn't fat when I was younger, but I had the womanly curves and got all the male attention. If we were around a guy my cousin would try to point out things - like she'd say something like "girl, your thighs are getting big". Jealousy, I tell ya.