The Farm, Mountain Shelter, Lodge and Residence do not require any food to run. However, toggling to give plain/fancy food to the building makes all work yards around it produce *2 or *3 goods respectively. A noble residence requires a form of food as a basic requirement and instead produces *1 good with plain food and *2 goods with fancy food (When built Noble residences automatically use plain food). Note: The cost of the other required resources remains the same whether or not any food is used.
Using plain or fancy food can help boost your supply of a certain good in return for food. This can be helpful if you are desperately lacking a resource. Note that just like any other required resource, a work yard that uses food will only operate when there is food available in the nearest storehouse.
Suggested uses:
Noble Residence - Butcher:
By setting the cost to fancy food the transaction changes from: 1 meat + 1 plain food ~ 1 fancy food, to 1 meat + 1 fancy food ~ 2 fancy food making the overall cost less by one plain food. Note: toggling a Noble Residence to use fancy food makes ALL the work yards around it use fancy food - if possible have a separate Noble Residence for work yards you will always use fancy food with such as the Butcher.
Noble Residence - Goldsmith:
One of the trade options available to every player at the start of the game is 2 rings ~ 4 gold. If you have merchants available, if the markerplace is reachable and if you set the Noble Residence with a Goldsmith to fancy food you are effectively exchanging 1 fancy food for 2 gold (and saving 1 plain food at the same time).
Noble Residence - Mint:
If trade is not available an alternative to the Goldsmith is the Mint - by setting the Noble Residence with a Mint to fancy food you are exchanging 1 fancy food for 1 additional gold (and saving 1 plain food at the same time).
Noble Residence - Blacksmith:
If you have a Stronghold but lack weapons setting the Noble Residence with a Blacksmith can help increase your supply of weapons and in turn help you build a bigger army.
Lodge - Hunter:
Towards mid-game supply of meat start to dwindle as less deer are available. Furthermore, deforestation stops the deer population from rising. Setting the Lodge with a Hunter to fancy food gives you more 2 more meat which in turn means more fancy food as the butcher will have a bigger supply to use.
Residence - Brewery:
Not enough beer can heavily slow players who rush for early/mid-game technologies or who trade beer for gold at the tavern. Using plain or fancy food increases the supply of beer and can help tackle this problem. Combined with the technology Purity Law, selling beer at a tavern can become much more profitable and can make a player rely a lot less on other methods to can gain gold for an army.
Not recommended uses:
Lodge - Fisher:
Toggling Fisher to plain food does not change the production overall as in total, only one plain food is made - it will instead may make the production slower or even stop if the nearest storehouse does not have any plain food. However, toggling to fancy food can be useful as it will convert 1 fancy food into 2 additional plain food.