Suppose each living unit had a 'food bar'. Suppose that food bar, when full, was at '24' (or '48' for mounted units). Imagine that each moment that the citizen is within the effective radius of a friendly 1) home, 2) drop-point or 3) caravan, that food bar would be maintained or raised (coming). Imagine that as that citizen leaves such a radius earlier mentioned, for each second the citizen is away from the food radius, the 'food' level drops by 1 point.
Imagine further, than once the food level drops to 0 points, the unit 'starves'. For each second starving, the unit loses 1 hitpoint. Imagine that when the unit reaches 1 hitpoint, and is starving, the unit either reverts to Gaia or dies.
Why is this significant? One of the main challenges in historic battles was feeding an army on the go. Battles could be won by attacking a supply chain. A castle could be defended largely by outlasting the stomachs of the attackers. I think it would bring a valuable and interesting twist to the game.