Your starvation problems is either from pollution or unrest. If its unrest, your citizens go on strike, and you lose production and hammers - build buildings that give you happiness or raise your culture level. If pollution is greater than health, it will eat into your food supply, hampering growth and eventually causing starvation. Build buildings that increase health (like aquaducts and public transportation), and try and acquire resources give health bonus' (clams, cows, pigs, ect.)