Goddes's Taste is another manhwa featuring an IB theme. There is no transformation, the changes happen very slooooowly throughout the series and they are not very noticeable either because of the artstyle.
Overall I do not recommend spending time to read it unless you like shoujo stories and what is basically a reverse harem. Alas, I still must post it for cataloguing purposes.
https://page.kakao.com/home?seriesId=54310637&page=1
Edit: Even though male IB is not as popular as female IB, I'll quickly mention the manhwa Dark Mortal where the male MC heals his disfiguring burn scar in Chapter 3, also featuring muscle growth making him ripped in Chapter 13.
https://mangadex.org/title/36161/dark-mortal