"Our grandparents used to make a point of not throwing away leftover food. Consumerism has made us accustomed to wasting food daily and we are unable to see its real value," Francis said at his weekly audience in St. Peter's Square.
"Throwing away food is like stealing from the table of those who are poor and hungry," he said.
Since taking office in March, Pope Francis has said he wants the 1.2-billion-strong Roman Catholic Church to defend the poor and to practice greater austerity itself. He has also made several calls for global financial reform.
Around 1.3 billion metric tonnes (1.43 billion tons) of food, or one third of what is produced for human consumption, gets lost or wasted every year, according to the United Nations' food agency.
In the industrialized world the majority of waste is by consumers, often because they buy too much and have to throw away what they do not manage to eat.
A U.N.-backed study released on Wednesday said simple measures such as better storage and reducing over-sized portions would sharply reduce the vast amount of food going to waste.
In U.S. restaurants, diners wasted nine percent of the meals they bought, partly because of a trend to increase the size of everything from cheeseburgers to soft drinks, said the report by the World Resources Institute and the U.N. Environment Program.
Francis said the "culture of waste" was especially deplorable given the prevalence of hunger in the world. The United Nations says hunger affects some 870 million people, while 2 billion suffer from at least one nutritional deficiency.
The Argentinian-born pontiff warned that too much focus on money and materialism meant financial market dips were viewed as tragedies while human suffering had become normal and ignored.
"In this way people are discarded as if they were garbage," he said.
(Reporting by Catherine Hornby in Vatican City, Alister Doyle in Oslo, Terrence Edwards in Ulan Bator, Deborah Zabarenko in Washington; Editing by Raissa Kasolowsky and Gareth Jones)