Unbeknownst to me, Dan Standing has been blogging! It’s not all breast expansion, in fact it’s not even mostly breast expansion. There’s a lot of miscellaneous type transformation that goes on in his stories and posts. Here’s one:

First to change were her breasts. Thanks to her weight they weren’t small, but they weren’t especially perky. That quickly changed. Regina was wearing a bra under her t-shirt, and she could feel under all the fabric that the skin of her bosom was drawing taught. It was like a faucet of warm molasses had been opened inside each fleshy globe, and it was clear that Regina was gaining a substance of mass that better displayed the depth of her boobs. Soft flesh was pressing hard against Regina’s bra, and a little voice inside her head spoke up, “If you’re getting better boobies, wouldn’t it be better to show them off?”

[Dan Standing's Ramblings]