Grammar: John keeps hydrated by drinking water.

I analyzed a sentence in my last grammar session and got a question about a similar sentence.

The old and new sentences are:

> Water keeps you hydrated.

> John keeps hydrated by drinking water.

For the first sentence I concluded that "hydrated" is an adjective modifying "you".

For the second sentence, I'll start with finding the verb.

Verb(action): keeps

    Subject: John

    Object: hydrated

    Prepositional phrase modifying "keeps": by drinking water

So "hydrated" is a noun. It's an object of the verb "keeps".