This is sort of nitpicking but may also help with people understanding the cost of food.
Although she tells you about costing more to last longer, it still is a little vague. I think the confusion comes from the dual meaning in English of food lasting (could mean either staying edible {to "keep" fresh} or enough to feed for that long {admittedly it should be one and the same but most people just do not think of it quite that way....as if they would eat spoiled food anyway})
Perhaps:
"I would like to buy food for one day" (need to drop the "s" anyway)
"I would like to buy food that would keep for 2 days"
And so on.
The mechanics are a bit strange also.
Perhaps it is to encourage you to spend what you need right up front?
Starting with less than one day supply of food:
If you top off the first day and then buy the second day, it costs 190 and 480 (670 total)(not 2 separate visits.....same visit and screen).
If you buy both days with one click of the 2 day request, it is just 480 (as if the additional second day is just 290 more).
Same for clicking separately on 3 days (190 + 480 + 850=1520) but if you first click on the request for 3 days of food it is 850 only. And one initial click on 4 days is 1400 (less than the overall total of the 1,2,3 jump)(Imagine that the same thing would happen with 1,2,3,4 but did not have enough money to test it).
Incidentally, from a technical standpoint, while I was jumping back and forth from game to forum with the alt-tab release, was able to duplicate that just hitting the tab key alone sent the game from full screen mode to window mode.