Some food experts estimate that up to 40 percent of all food in most wealthy countries is wasted every year. The United Nations' Food and Agriculture Organization says more than a billion tons of food goes to waste each year. Food waste also takes place in developing countries. Even as so much food is wasted, experts estimate that one billion people are underfed. Hundreds of millions of people go hungry each day.

Danielle Nierenberg is president of an organization called Food Tank. Her group studies food issues. She says much of the food waste in developing countries is blamed on bad roads, which slow the transport of goods to market. Another problem is a lack of food storage centers. She adds that food waste in wealthy countries is more an effect of people who buy more than they can eat.

VOA spoke with Danielle Nierenberg at a meeting of the Barilla Center for Food and Nutrition in Milan, Italy. Delegates to the meeting called on international leaders to improve food security. They called for reducing overeating and waste in both rich and poor countries.

Ms. Nierenberg says the amount of food wasted each year shows that there is enough food to feed everyone. In 2012, UN Secretary-General Ban Ki Moon launched a campaign called the Zero Hunger Challenge. He asked farmers, businesses, governments, scientists and others to work together to put an end to hunger. The campaign calls for increased productivity and income on small farms. It seeks support for sustainable food systems -- systems that are able to last for a long time. And it calls for an end to malnutrition in pregnancy and early childhood.