Food is an important resource in The Hobbit: Kingdoms of Middle-earth.
Farms increase the food production of the city, along with boosts from Research in Fertilizer which allows you to increase food production by 10% per level.
By conquering Lakes and Grasslands your food production increases by 5%*[level of Lakes or Grasslands] conquered.
Food is needed for the training of troops, buildings and the upkeep of troops, (troops trained in City Wall don't require upkeep). Food can be protected from attacks by the Vault.