Maybe make an army food supply, similar to war chest. If the region is starving, food comes from war rations. This could also be an excellent way to reintroduce the steal food looting option- put it in war rations.
If you played with the potential feature some, it could really make being an army sponsor lucrative if you could sell/buy war rations in market places.
Imagine looting the food of your enemy, and then selling the surplus that would rot to your starving ally.
However, a potential abuse would be to loot 700 miles away from your own starving capital, and then the sponsor sells the food the same turn while at home. Maybe make the sponsor purchase the food at a fixed rate, and it goes into the granaries of the region is based out of. Since the sponsor essentially owns the army it should be a low price, but definitely something to prevent instant food sales from halfway across a continent.
