Population and upkeep

Population is the crop the buildings eat. Troop upkeep is extra crop on top. The number in the header is production minus both.

Buildings

Each upgrade adds population — crop the buildings eat. That is why a “finished” village still starves if you drop a Great Warehouse without more cropland.

Troops

Each unit has an hourly crop cost. A hero is 6. Roman cavalry can drop by 1 once the Horse Drinking Trough is high enough (Equites Legati 10, Equites Imperatoris 15, Equites Caesaris 20). Wonder villages halve troop crop.

Why this bites harder here

Upkeep runs between play windows. A train queue you started near the end of a session will keep eating at 02:00. The moment the granary hits zero, troops start to starve, one unit at a time, even if nobody is logged in. Deaths are spread fairly: every stack the village feeds (your own and allied reinforcements there) loses the same percentage, and heroes die last. Leave a surplus large enough for the whole gap between sessions, not just the next ten minutes.