Dancer claims she was fired after she went from a C-cup to a D-cup. According to Alice Alyse, after she returned from leave to the show "Movin' Out" she needed new bras sewn into her costumes although she'd neither gained weight nor gotten implants.
I'll leave aside the question of whether Alyse's suit against the production company is justified. But I'm here to tell you: Your breasts can grow after puberty, whether you gain weight or not. I know. It happened to me. Sometime after the age of 30, my breasts took on a life of their own. Like Alyse ("When they hired me I wasn't flat-chested. I mean, a C means -- ya got boobs.") I was by no means flat-chested. But apparently my boobs weren't satisfied with their preeminence and whether I gained or lost weight was immaterial: They were growing.
Of course you can't go by bra size. I'm pretty sure they've monkeyed with cup size over the past decade or so, changing a traditional A to a B, a B to a C, etc. They did the same thing with women's clothing size in reverse. Feeling great about wearing a size 6 for the past 20 years? Better step on a scale cuz that size 6 is more akin to the size 10 of a decade ago.
I guess manufacturers have been doing this to make women feel better about themselves. Flat-chested women can now console themselves with a B-cup. However, I think I can speak for those of us on the other end of the spectrum when I say that we have no desire to advance beyond the fourth letter of the alphabet.