For food that give semi-permanent stat boosts, go here.
The primary use of cooked food is the temporary stat boost the food gives. Do note that logging off resets all food bonuses. Each food gives a specific boost to key abilities. Some of these foods will also affect your appearance*. The higher quality of the food (number of stars), the higher the boost. Here's a list of the foods that give the biggest boost in each category:
*Listed as Physical Change.