Grammar: "Hydrated is a good way to be."

On FI discord server, the following problem was presented:

Context:

> Water keeps you hydrated. link to analysis

> John keeps hydrated by drinking water. link to analysis

curi said:

> Do you think this is grammatical? "Hydrated is a good way to be."

> or "Hydrated sure beats dehydrated!"

They seem grammatical at first glance.

Verb(linking): is

Subject: Hydrated

Object phrase: a good way to be

    Object: way

        Adjective modifying "way": a

        Determiner modifying "way": good

  

interrupting... I initially thought "to be" is a prepositional phrase, but I couldn't fit "be" as the object of the preposition because "be" can't be a noun. I looked up apple, Merriam webster, and Cambridge dictionaries, and none of them said "be" could be a noun. I also did some google searches looking for any grammar analysis for things like "to be" and "way to be". I didn't find anything directly talking about this issue. 

So at this point I'm undecided on whether or not that sentence is grammatical. I'm going to think about the second one.

> Hydrated sure beats dehydrated!

Verb(action): beats

    Subject: Hydrated

    Object: dehydrated

    Adverb modifying "beats": sure

As long as "hydrated" and "dehydrated" can be a nouns, the above analysis works.

Back to the first sentence. I want to consider an easier sentence.

> I am hydrated.

Also:

> I am old.

In this one, "old" is an adjective. I found this sentence here. It gives many examples and in all of them the structure of the sentence is Noun + To be + Adjective.

Then I skimmed the FI grammar essay and found this:

> The complement is a noun or adjective which is linked to. (Adjectives are explained in step 4.) In The house is very big., the complement is “big”. Bigness is the thing that the house is linked to.

So I think I made some mistakes in this post and in my previous grammar post. 

In the previous grammar post, I analyzed "John keeps hydrated by drinking water." In order to treat "hydrated" as an adjective and as the complement of "keep", then "keep" would have to be a linking verb. 

I'm stopping for now. 

There was more discussion in FI discord about how "keep" works.