I know to some extent this is already enabled- If you go to a starving region and have a caravan of food, you feed your men from the caravan.
If this concept could be taken to the next level, we could have armies carrying food around with them. What happens now, is when one realm invades another, their troops steal food from the region they are in to feed the soldiers. Unfortunately, this happens implicitly. AFAIK, there is no notice saying that enemy realm stole and ate X number of our bushels when they invaded. If a feature like this was added, if the enemy hadn't brought a caravan of food with them, they could *
explicitly* (perhaps a button under loot) decide to take 5-10 bushels to feed each of their units. This would generate a notice to realm that the enemy had looted X bushels.
Why? It adds flavor to the game. The invaded people can have propaganda saying the enemy stole X bushels. On longer trips, invaders have to bring caravan trail of goods. This also makes it easier for smaller realms, while giving larger realms some more challenge. Treaties can be signed between allies on whether or not their food can be eaten while their allies armies are passing through (gives passage rights a whole new bite).