Skial

Yes.

Disappear completely.

You will taste like eggnog

hopefully the second option beca- *this user has been banned*

Well as you are eating yourself your body will begin digesting your flesh like it would normally, turning it into feces eventually. Obviously you can't eat your whole self and expect to digest all of it since at some point you will die from this. When you die however, your body will void its bowels while undergoing rigor mortis.

So if someone discovers your body after you die from eating too much of yourself, then they will stumble upon your partially eaten corpse and some shit in your britches (assuming you were wearing clothes).

So my answer would be you neither get twice as big nor disappear, but rather it will just look like you got mauled to death by a zombie which is equally cool in my opinion.
TL;DR Don't eat yourself. It's bad for your health.

Well, if you eat your own dick it probably becomes twice as big, but I'm fairly sure that this theory doesn't apply to all aspects of self-consumption