Fill up your tummy full to optimum level before boarding the train if travelling from HWH. Only little snacks and tea available at KGP and BLS (at BLS it again on luck). No food available till KUR.
As its an overnight train, so food doesn't matter much, but most important keep a bottle of drinking water ahead of boarding. At night time no seller board it and hardly the train stops anywhere for long halts, so filling up bottles from any station is forgettable affair.