[--]

Jyutping faat3 fan5 mong4 sik6
Pinyin fā fèn wàng shí

Definitions (Wiktionary)
  1. phrase, idiomatic
    to study or work hard, neglecting one's meals; be so immersed in work as to forget one's meals

發憤忘食 [发愤--]

Jyutping
Pinyin fā fèn wàng shí

Definitions (CC-CEDICT)
  1. so dedicated as to forget one's meals (idiom)