When you're food stocks are low, sometimes you citizens engage in hording. One person will take more than his fair share of food back to his house, and this will cause the rest of your citizens to starve.
To avoid this, make sure to have at least one year of surplus food. Each citizen eats about 100 units of food a year.
Another way to avoid hoarding is to build a market. When you have a market, citizens aren't allowed to hoard.
In the early game, just make sure you have educated gatherers working on one to three forest pods (forester/gatherer combo). Eventually, when you have more resourced available, you can build a marketplace.
One thing I do when I first start out is to lay down the foundation of the marketplace, and then plan my city around that. You can lay down a building and then pause construction so that no resources are spent, but you'll still see the layout, and can use it for planning purposes.