人是鐵飯是鋼 [－－铁饭－钢]

Jyutping jan4 si6 tit3 faan6 si6 gong3
Pinyin rén shì tiě fàn shì gāng

Definitions (CC-CEDICT)
  1. one can't function properly on an empty stomach (idiom)
  2. an empty sack cannot stand upright