Your best bet to cut back on food costs is to take a cab from the airport and tell the driver to stop at the grocery store on the way to the Comfort Suites because all of the local shops are owned by the Atlantis (and thus are all horrendously overpriced).
This is a lot harder for them to do than you'd think, especially when the player is unrated (which he/she should generally be doing if they're a consistent winner). Pocketing 1X your EV per hour is very manageable and can go easily unnoticed.
There are other ways to manufacture losses as...
From the casino's perspective: I would imagine that a consistent/life-time winner would be scrutinized before a schmuck who pockets a few greens per hour.