In Ultima VII (both parts), eating is absolutely essential for keeping your party at full strength. However, each food item has a different feeding value. The feeding status of a party member is indicated on a 31 point scale, with 31 being full and 0 being starving to death. In this table, the feeding values of the various food items -meaning how much of the bar they refill- is shown.
The table tells us that all kinds of meat and cheese are very filling. Fruits and vegetables on the other hand aren't, and you shouldn't bother with drinks. Silverleaf Meal is totally useless and expensive (30gp in Trinsic!) and should be avoided.