No food in the house? I'm having a hard time with this question, I absolutely just refuse to not have food in the house.
Honestly, most meals I cook are free or extremely cheap.
I try to plan ahead with sale cycles. If I can get cereal for free this week, I'll get approximately 3 months worth to coincide with the next (assumed) similar sale. Ditto for most items I buy. The only thing that really limits how much or what type of foods I'm able to stock up on is the space available to me. I have one chest freezer that is consistently full of hunted meat, veggies, and cheese. Pasta and rice are items I refuse to pay for and go a long way toward stretching meals and keeping you full. I have chickens for eggs, or meat if any of them decide to become hooligans. I forage blueberries, strawberries, raspberries, etc and freeze or can. Out of season fruits or vegetables, milk, and a couple baking staples are the normal grocery expenses for me, and if need be I'll cut out fresh fruits or veggies for frozen if I simply can't afford it. Meats like hot dogs or whatnot I'll buy if the price is right and stock up, or just not buy.
I've gone hungry before in my life, and it is something I refuse to ever have my children experience. I may not always be making our favorite meals, in fact, some meals none of us are really big fans of lol But our bellies are always full, and I do whatever I need to do to stay within budget. Can't afford groceries this week? Well, I'll scrounge up a couple bucks to keep milk in the house or some bread, and the rest I'll pull from the freezer, my pantry (one set of shelves hidden in a bedroom and slim totes under my bed), and avoid the supermarket. I simply can not allow myself to not have a store of food on hand for meals when the budget isn't there for me to bring in groceries...I've experienced empty cupboards, experienced opening a fridge to a container of baking soda and assorted condiments. Refuse to ever see that again, or worse, have my family see that.
In that baking soda situation, 3 days of meals? We're getting what I can get for free for those 3 days, plus milk. Hunting season or not, if I have to I will do that. If it's summer 'produce' can be found. If it's winter, then I'll probably spend the remaining amount of my $7 on oranges, bananas, or another lower cost/higher benefit produce item.