How to translate: 人是铁，饭是钢，一顿不吃烦得慌. What is the logic? 人是铁，饭是钢，一顿不吃烦得慌

I can not really figure out to translate this sentence. I guess it basically means that not eating is a bad thing. The first sentences - do they indicate that "iron" and "steel" belongs together, and so does "man" and "food", and it there is one, there better be the other, and thus - not eating is a terrible thing. 

Would this be a correct understanding - or what else is the logic behind this sentence?

Thank you
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.