those fridges are 31 liters.you are heading to the store after 5 days whether you want to or not.
A 31L fridge depending on how it is loaded and what is put in there can and will hold enough food for a couple of two for a couple of weeks, My 47l holds enough for just me for 43 Days, If a person is carrying fresh Vegetables and can foods then I can stretch it to about 50 to 55 Days,
It all depends whether a person eats only foods out of the fridge or mixes it with other non chilled foods, I own the 47L and the 78L/82Qt, In the 47L at present I have about 9 cooked meals in there 2Lbs of frozen Veg about half a dozen Sausages a Small Joint of Beef and a Pound of Minced Beef and 4.8 pints of Milk and a Pound of Butter and Half a Dozen Eggs and the ARB is less than half full and when cooked up that is enough to last me about 20 Days If I add a pack of pasta to the minced beef and a few Onions etc,
The key to having a well stocked fridge is to freeze it right and remove all that over sized supermarket packaging, Pre cooking and pre freezing meals beforehand is a major space saver and cryovac foods are even better because they keep for weeks and you don't have to run the fridge/freezer at such a low Temp, Remembering that we are talking about a few weeks travel not storing supplies for the Winter, So those cheap cryovac machines from Amazon are worth their weight in Gold,
After many hours of testing I am starting to wonder if I will ever get to use the 78L / 82Qt ARB, Like all things I made a Plan the use the 47L as a Fridge and the 78L as a Freezer but with the right temp setting and packaging the ARB 47L has both tasks covered Admirably and still with Room to spare,
EDIT:- I just Added another 4 Packs of Beef and another 4.8 pints of Milk X 2 which is close to 1.2 US Gallon and I still have a heap of room left.