How to translate: 人是铁，饭是钢，一顿不吃烦得慌. What is the logic?
The idiom's meaning is reinforced by the rhyme. I think you have the basic meaning correct. Maybe if you rhyme it in English it'll come out more like the Chinese:

"People are iron/Rice is steel/You'll feel like crap without a meal" - not a literal meaning, but conveying the gist.