Currently in Age II players can pack troops into a regular city or Historical City with zero food and the troops won't die. They can just keep packing and packing and drafting and drafting and eventually the city may have 500 million troops in it. This will make capturing cities impossible and create armies of insane numbers.
Using food in any way as a army size limiter is out of the question here. The second we introduce food as a limiter in any way is the second players who farm the most win. And when that happens Age II will become Age I. So all of these ideas are foodless ideas...
Suggestion1 - Troops in your city are dismissed (or go into fugitive camp) after a certain period of time.
This will allow players to build armies as big as they need. Say the newly trained troop can stay idle in your city for "x" time. Long enough to train and store troops required to solo a L16. But not long enough to allow a player to amass a army of insane size. In chess there IS a time limit. You cannot keep pieces on the board forever without moving/using them.
Suggestion2 - Hard Cap on troops. Say each city is limited to only holding 2 million troops. This will force players to use more strategy than brute force. HOW the player decides to use their troops will determine if they win the battle or not. Just like chess, HOW you use your pieces determines if you win or lose. It will also force players to use their troops and kill off troops before they can train more. A hard cap is hard to exploit.
Suggestion3 - Troop handicap. The larger size army a player has the more penalty that player gets. The penalty is basically a handicap like golf. For example, The more troops a player has the worse their heal rate. Or the more troops a player has the lower their defense/attack goes.
Suggestion4 - Training time slows as army increases in size. The more troops you have the longer it takes to train them.
Suggestion 5 - A combination of a hard cap AND Fugitive Camp. Troops are hard capped at "x" million per city. Anything beyond "x" million goes into fugitive camp. With this idea, lack of food does not send the troops into fugitive camp. Rather, going over the cap puts troops into fugitive camp.
Suggestion 6 - Reintroduce refuge but with penalties that are less harsh to cater to more casual/inactive players. (this is a food related limiter but have added to suggestion list)