SAT - Writing & Language
The meaning of both the phrases is the same. Healthy is an adjective while healthily is an adverb. One will hear the words 'eating healthy' used more often than 'eating healthily'. Grammatically it is correct to say 'eating healthily' but many people and authors use 'eating healthy'. It's a matter of choice to use either, as both the words convey the same meaning. And off late healthy has been used as an adverb too.