In real life he could not be completely invisible, and would recover.

Oh come on I'm tired of this it's just a movie crap and that it doesn't have to make sense.
Well if movies don't have to make sense than all of these debates don't have to make sense to people who don't care about making sense in the first place.

All of this is just for fun and if some "god forbid" logical conclusions shoud come out of this then so what?!?

I'm just sick of all of these "it's just a movie" posts. If you don't have anything better or smarter to say than just don't say it!!!

it's a movie, it doesn't have to make any sense

"That always bugged me that we were to believe that everything he ate went straight through him, into the toilet, instantly."

He's invisible, not intangible. Was that a scene in the movie? I don't know. I never saw it. That's pretty lame if that's the case.

I don't think he would necessarily become blind, or have food or replaced cells showing through. If becoming invisible was possible, I think it would work much like how I think the Predator did it. He would make all incoming light rays curve around him then continue in the same vectors they had when they reached him. That way, he reflects no light, just creates a detour for light, then a continuation of it, and therefore appears invisible, although none of his cells are even invisible.

The food he consumed would eventually become invisible as well, hence his poops were invisible as well... must have been a pain to wipe

You should check out the novel this is based on; it addresses a lot of these points as issues Nick himself has to deal with

This movie alludes to some of it when Nick demands his molecules back -- the novel Nick still isn't a scientist, but learns enough to be able to explain to Alice that his molecules have been changed to "potentials" or some such, meaning he can still eat, but whatever he digests gets turned into more of what he already is (i.e., invisible).

He also gives off no scent (so dogs can't track him) and dirt sticks to him and his clothes less than it would to visible surfaces.

It really gets into the weeds of his existence, including how he sets up a false identity, accounts, etc., all while trying to stay ahead of Jenkins.

Here's a quote:

"The theory seems to be that these objects are not built up out of the same subatomic particles as other physical things. Instead, they are composed of different particles, or perhaps units of energy, but arranged in the same structure as before. Or perhaps they are largely the same particles, only interchanged somehow. There are differing schools of thought. In any case, you have an object with roughly the same properties as the original, except that light passes through it without any refraction. Specific gravity is slightly lower. Mechanical bonding seems to be poorer"