What does the Cafeteria do?
Food cost cannot be a negative number. If your Food cost reduction exceeds your total food cost, you will have a 0 Food cost and your Practical Income will equal your Food Income.
For example, at Lvl 10 the Cafeteria can reduce Food cost by 13,000 per hour. If your Food cost is only 10,000 per hour, when the Cafeteria is active your Food cost will be reduced to 0. Your Practical Income will equal your Food Income, but you will not get an additional 3,000 Food per hour .
Remember to check your Cafeteria status from time to time to save that hard-earned food.