Speaking to crowds gathered in St Peter's Square on Sunday, he instructed people to "examine their conscience" regarding leftovers.
"I'm thinking of people who are hungry and how many leftovers we throw away," he said.
The leader of the Catholic Church reflected on the biblical story of the boy who gave five loaves and two fish to Jesus and his apostles.
He said after Jesus performed a miracle and fed the 5,000, Jesus ordered the apostles to "Gather the fragments left over, so that nothing will be wasted".
He went on to say: "What do you do at home with the lunch you haven't eaten? Do you throw it away? No! If you have this habit, I give you a suggestion - talk to your grandparents who lived through the post-war period, and ask them what they were doing with their left-over food."
The pontiff shared ways to reduce food waste.
"Cook them up again or donate them to whoever can eat them -who's in need," the pontiff suggested.
Stay up to date with the latest news stories from a Christian perspective. Sign up to our daily newsletter and receive more stories like this straight to your inbox every morning.
