I've been hearing people say:
I've been eating healthier lately.
This sounds like bad grammar to me. The word "healthier" is an adjective, so it should modify a noun, but in this sentence, the speaker is using it to modify the verb "eating". That makes me think that the speaker should turn "healthier" into an adverb by adding "-ly", but the result doesn't sound right to me either:
I've been eating healthierly lately.
I thought that maybe using "healthily" with "more" would sound better, but that also doesn't sound right:
I've been eating more healthily lately.
I think this is grammatically correct, but it seems that I'm going out of my way to be correct. I don't like that either. The only alternative I can find is to scrap "health" completely and replace it with a synonym:
I've been eating more nutritionally lately.
What do you think?