Balance of Nature
Nature is not actually in balance. Rather, it is a series of interdependent corrective forces, with an ever changing set of values. More of a dynamic equilibrium than a balance.
Rats eat grain, and their populations grow wildly to match. Predators predate the rats, and their populations grow while the rats decline. If either population grows too much, food becomes scarce. The creature that goes hungry, will either breed less or die outright. The "balance" is never a static equation, the variables are always changing.
This suggests that if a human population goes hungry, there are too many people there. The historic traditional approach is for these people is to move (migration) or starve (famine). If there are people already in the lands where you are trying to move to, the other tradition is war.
Either way, the basic force at work is quite natural.
Artificially propping up a system might sustain a population past a temporary food shortage and bring it to the next bounty. This seems to be a normal human instinct, and as long as that infrastructure sustaining the population does not collapse, all will be well.
The problem is that as long as you feed a population, it grows, and if overwhelms the infrastructure supporting it, you have quite a potential for disaster.
Nature tends to correct any imbalance.