It is fine as-is, though it may sound more natural to say, "I always have and always will eat ..."
This sentence is similar in purpose to the consequent of a zero-conditional. (If/when X happens, then Y happens.)
The purpose of the zero-conditional is to describe real situations which are always true. The sentence being constructed here is doing just that. In a zero-conditional, the verbs in both parts are in the simple present. So, in this case, I think formatting the verb in only the simple present is acceptable because it matches what an English speaker would recognize as the consequent of a zero-conditional.
If omitting 'eaten' is bothersome, the sentence could be reworded as a true zero-conditional, "When I eat, I eat food."