Board Thread:General Discussion/@comment-28096256-20160413001736/@comment-27392440-20160416204323

I hope you don't mind if I post my own theory on this as I've given this some thought too (though I admit this is just speculation on my part and might be overthought a bit).

There are 2 key things I think are required to reach vasto lorde status besides a base power level: being able to enter your inner world and perhaps a special "diet".

Entering your inner world would probably be crucial so you can "digest"/kill the hollow souls you've eaten so you can make it your own power rather than merely being the power of a mass of hollows that are trying to drag you back into the collective conciousness of a gillian (which would explain a vasto lorde shrinking as them becoming their own being rather than a huge composite of many).

The idea of a special diet affecting their growth came when I wondered if anything special would happen if rather than eating other adjuchas they ate pwerful shinigami or even a vasto lorde somehow. Going after especially hard to get souls would not only give an evolutionary push but would also nourish them in a unique way from other hollows and push them to the next stage.

There may even be alternate methods to feeding on others as Hallibel and her fraccion (in the anime backstory of her time as a hollow) tried to never kill their enemies if I'm not mistaken, yet none of her fraccion regressed to gillians or looked like parts were eaten to stop growth. Starrk/Lilinette may even be an example of growing by learning to communicate and bonding with your inner hollow, much like shinigami and zanpakuto do.