There's not exactly any need to be plump to have poorly fitting costumes in H!P
Regarding Zukki what about her and the agency, I'd love to have some explanation as I may have some missing part?
About Chel feeling not confident, she had gained weight coming back from her English training, but then again back to the egg and chicken.
I also want to point that Fukuchan isn't skinny by far, that she gets dissed online for it, and that the agency never put her in the back, because she has other points to sell.
I know it's unfair, but Fuku-chan's visual overshadows how she doesn't look as skinny as other idols
And regarding Chel, she has some points that are not typical of Japanese girls. It includes not being skinny. Sadly, most Japanese fans are still obsessed with being skinny, but I think when girls look too skinny, they also lose their charms. But then, it's Japanese fans who they have to prioritize, so I understand why companies treat not-skinny girls that way.
Let me bring out the topics regarding one former member: Haa-chin tried to look so skinny that even the manager encouraged her to eat more, and she wasn't promoted as much as other members. Key point: being skinny doesn't guarantee the idol gets promoted, but not being skinny means almost closing the door for further promotions.