Think you need more vendors on the market; people prefer to get their food via the market and not from the warehouses. But if you don't have enough vendors to take the food from the warehouse to the market they do take it out of the warehouse. But food taken out of the warehouse is always the max someone can carry while via the market it is more even distributed. The same for your laborers, they need to bring the food from the gatherer or hunters to the warehouses, maybe a bit less people producing food and more into transporting.