以食见人：a person can be understood/judged through what (s)he eats.
人如其食：a person is like what (s)he eats.

I searched on the Internet, “人如其食” is the most commonly used translation for "you are what you eat", but in general, the Chinese cannot understand what "人如其食" immediately (but we can understand “人如其字”(a person is like his/her handwriting) immediately)and they also have to guess what it means, but "以食见人" can be understood by us immediately and is more elegant than "人如其食", So, I prefer "以食见人"