Many English words can serve as verbs and nouns without changing form. "Nutrition" is not one of them (I'm not sure it even has a verb form). The speaker here is playing with that by deliberately (mis)using the noun "nutrition" as a verb, to emphasize that his video is about nutrition, and to imply that the viewer may not know/do/think/understand as much about nutrition as he does. It's half a joke, and half a ploy for the viewer's attention. You will never see it again outside of this video (at least, I really hope you won't).

Bro, English is a living language. It's always evolving. Influencers play with words, then these words got registered by dictionaries. Yes, it's possible to make the 'nutrition' noun a verb. Also check out these links: https://www.urbandictionary.com/define.php?term=nutrilicious https://www.urbandictionary.com/define.php?term=nutriate Have fun.

I honestly wouldn't even say that 'relaxed' or 'informal' speech are the right ways to describe the appropriate use of something like this. It's not an improper usage that a native English speaker, as a result of the informal grammar of their dialect, would EVER say naturally. The word 'nutrition' is being deliberately misused here so that it fits the form of the "bro, do you even lift?" meme- "bro, do you even [know/understand/study] nutrition" would be proper but doesn't match the cadence of the meme. Let me put it this way: if someone used 'nutrition' in this way with a Russian accent, and it wasn't used in EXACTLY that sentence, it would sound like a mistake.

I don’t see why you can’t it’s clear that it’s used in comical manner so why not obviously you wouldn’t write that in an essay or ask your professor about it, but for a “bro” - sounds good enough

https://www.youtube.com/watch?v=KNQwfd2kLJg&list=PLJRbJuI_csVAMq2VPr96h6TL4Y98rfznM&index=9 He said in the beginning 'Do you even nutrition?'.