Food and drink are an oft-abstracted subject in roleplaying games. In many cases the need to eat is represented purely by purchasing trail rations or survival days, and taking in-character breaks for breakfast, second breakfast, elevensies, lunch, tea, afternoon snack, or whatever other meals one wants can bog down the game. Players will also chafe at the bit if the DM spends more than a moment describing a given meal—taking the time to lovingly describe the savory banquet of rich and delicious food laid out by the local lord as he requests the PC’s help may seem like an important part of setting the scene, but you may find players yawning or surreptitiously checking their watches if you take it on too long. Worse, if you do it while the players have empty stomachs, they might call a hold on the game to go eat!
Food and drink can, however, reveal a lot about your setting. Wealthy nobles will certainly set a richer table than common inns, and oppressed villages under the thumb of a cruel lord might have even less to share. In a town with a shortage of food due to poor harvest or heavy taxation, one might encounter poachers or half-starved beggars, or pass by fields, fallow from rotten crops, their farmers sitting idle and hopeless. As a tool for description, the effects of having (or not having) enough food can be more valuable than the description of the food itself.
When applied directly to PCs, it can be used—albeit sparingly—as a way of leading them into new adventure. You can have them stumble into an ancient ruin or bandit camp while hunting to supplement their store of rations, or be arrested for poaching and sent off on some mission in lieu of prison time. In some settings, the search for food may become an adventure in and of itself, though the core assumption of the game seems to be that food is fairly readily available, and you should make sure your players are on the same page as you with regard to changes to that basic assumption.
For the real world-builders among us, thinking about the types of food and drink available can be an interesting exercise as well. What crops and livestock are common to what regions? Are most foods Earth-equivalent, or are there a large number of fantastic crops unlike anything found in reality? What other uses can the crops be put to—dyes, perhaps, or cloths? How common is meat? Is fish the staple food? What kinds of spices are known, and how much money is there in the spice trade? These kinds of questions can help in defining a wide variety of elements beyond the obvious question of “what’s for dinner?”