Hunger is caused by many things. One of them is how chronic hunger is making the hungry stay hungry. The adults in the families go to work to get money for their famalies food. But they cannot get enough money if they don't work hard enough, and since they are getting no nourishments to work hard, so they are back to the begginning, hungry.
Wars are another reason hunger is caused by. The fighting interrupts the farming for food, and the hungry cannot get food. Also, sometimes the countries fighiing in the war will starve their other opponent by destroying the food, and contaminating the water, having to fore the farmer to leave it's land. Sometimes during the war, the hungry are forced to leave their homes, and are left hungry.
Poverty is probably the main reason people are hungry in the world. The children's gaurdians get around $1.25 a day as their income. So they can barely afford the food. When a family goes into poverty (that was not in it before) they spend the little money that they have on the nessecities. Which leaves them without any money for food, which also leaves them hungry.