Two meals in sixteen hours is not unreasonable when you consider that there'll be a little self service bar, where pax can get snacks, drinks etc. as they wish.
Good on SQ, a leader once again.
As to the fuel requirement, I was just trying to work it out myself and came up with around 126t, based on 18h at 7t per hour, on average, but then you need to add in holding time and a diversion to SFO/SJC or LAS, so that probably brings it up to around 135-140t, plus OEW (170.5), plus pax/freight (say 20t), still well within the MTOW of 365t.