Food wasted by consumers is an enormous economic problem and nations should ensure excess food is given to the hungry instead of being thrown away, agriculture ministers from the Group of 20 leading countries said on Friday.

The two-day meeting in Istanbul has focused on problems of food security and nutrition, including the impact of climate change. A reduction in the amount of food wasted would improve food security, the ministers said in their final communique.

"We note with great concern the significant extent of food loss and waste ... and their negative consequences for food security, nutrition, use of natural resources and the environment," the ministers said.

"We highlight this as a global problem of enormous economic, environmental and societal significance."

An estimated 1.3 billion tonnes of food, or roughly 30 per cent of global production, is lost or wasted annually, the U.N. Food and Agriculture Organization (FAO) said last year.

U.N. agencies said this would easily feed the world's 800 million hungry.

In developing countries, food is lost because of improper storage or transportation, while it often just wasted in rich nations.

"In the developed world, it's really about reducing the size of portions. It's about making sure people understand precisely when food is no longer good for human consumption," U.S. Agriculture Secretary Tom Vilsack told Reuters in an interview late on Thursday ahead of the meeting.

"I think there's a tendency to throw things away more quickly than need be."

Food is the single largest component of solid waste in U.S. landfills and is a large producer of methane gas, Vilsack said.

In the United States, methane is the second most prevalent greenhouse gas emitted from human activity.

To fight the problem of food waste, countries need better estimates of the amount of food they waste, as well as the economic impact of food loss, the G20 ministers said. – Reuters