Green’s Dictionary of Slang

1. (US) a hunger for narcotics.

1920

F. Williams Hop-Heads 26: A week or more passes of that awful agony, and then comes what we call the ‘long gut,’ the ‘big hunger’.

2. (W.I.) a greedy person.

1956

in Cassidy & LePage Dict. Jam. Eng. (1980) 279/1: lang belli, lang gut / a greedy person.