no food in stock have a secondary effect... you need food for research and construction...
food and army eating it is really a problem at low level... once you reach lvl 21, production double...
making troop die when food run off will only be a problem for smaller player...
i am lvl 25 with a lttle more that 12 million troop, 1.5 million of them are t5... with my rest armor, i yet produce 9 million food by hours
i am in red when i am in attack mode but never reach zero due to high capaciy farm and capacity
as destroy huge armies, it is possible... amount of troop is one thing but hero, shaman, armor and research are more important
for example, look below one of my attack... send only 500k troup, 200k are killed... but i have kill 2.8 million ennemy ( 80% who is the max ) in their own city... spy is my speciality... sometime after spy, i see a ennemy with a lot of archer... then contact a clanmate who have the expertise horse since horse have a 50% bonus on archer... and he do the attack
and for the very huge one, you have always onslaught too