I think this is a rare content among various types of BE, but I find the concept quite interesting, and it would be great to find as many as possible. Basically, it is a breast expansion achieved through moving one's fat into her breasts. I will start with some examples:
Crayon Shin-Chan movie 13 (This was posted before, but I am reuploading it since all the old links were broken)
"The Ghost Bride" by Sapphire-Foxx (3:00-3:10) (I know it is from a TG sequence, but just focus on the BE part please)
Taiwanese drink commercial