If nutritional needs are forfeited (vitamins maybe) then I'd go with this line of reasoning:
Eventually, even the finest of foods eaten every day will become the standard, and only go downhill from there. Anything that makes that food special will eventually start to grate on your taste buds and with time become despised.
Therefor, the best thing to do is to go with the most tasteless food imaginable. I don't know if that's plain rice, unflavored tofu, etc. because my culinary pursuits are generally on the tastier side of the spectrum, but whatever is as forgettable as possible. The closer to neutral the food is for the life sentence on my tastebuds, the less it can fall from good to bad.