yeah but the G-Embryo could again be argued to have a better form of energy storage because it's not human, plus if memory serves it bursts out of a person, killing them then you don't see it for a while, it could be argued that it ate some dead bodies like nemesis. This carries with Jack who could've been gifted some mass from the mutamycete directly. Alcina is in that "Anime" rules category because while it could be a case like the G larvae it's not as well explained. she might be the same weight as before she transformed because she can also fly even though her wings are too small and she has a similar size to the popokarima, another giant flyer.You can still find in the game how gigantic Dimitrescu, who has mutated into a dracula-like form, complains of exhaustion. How much she needs blood, a lot of blood. It's the same with Jack Baker, who cried after mutating how hungry he was.
These forms are especially dramatic owing to the first-person perspective, but from a different perspective they are not even close to the largest monsters in the series.
And they is hardly different from G that, in front of Leon or Claire in the original second game, grew a functioning tissue in a matter of seconds from basically an embryo. And now imagine that this is not an embryo, but a three-meter curvy woman.
Super fat storage is the only way to explain alot of the cadou transfomations, this works for G, but not for the Cadou which seems to be a Easy Bake T-Virus.