。
Do you know what true hunger is?
Literal
True [possessive-の] hunger [topic-とは] what-kind thing [question-か] know?
本当の空腹とは ('what true hunger is') uses とは as a defining topic marker — 'as for what true hunger is.' どのような事か embeds a question ('what kind of thing') inside the main sentence. A rhetorically challenging question.