I've got a really strange occurrence. I've got a lot of food- so much food that I've got to take people off food production or I can't build new storage barns fast enough to hold my food excesses. But my population are still dying of starvation. I've built some markets and they too are full of food. Why on earth are people dying of starvation when I've got so much food?
"Having Food" is not synonymous with "Being able to Eat food".
If you have plenty of surplus, and still people dying to starvation, the problem likely exists within your supply chain. In my experience, this usually means people are involved in pathing very long distances, such that they starve on their way home to eat.
Use the info panel to follow starving citizens. Where are they going? Where are they coming from? I've seen at more than one Let's Play where folks have mistakenly designated buildings far away, long before a sane path to reach them exists -- the end result was people walking towards the structure, giving up 75% of the way there when hunger kicked in, starting back, and dying before they reached their homes.