Study: US Wastes 40 Percent of Its Food

A new study claims that Americans throw out about 40 percent of all their food, and food waste per person in the U.S. has increased 50 percent since 1974, according to LiveScience .

The study, conducted by the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) and published in the journal PLoS ONE , calculated the difference between the U.S. food supply and what's actually eaten by using a model of human metabolism and known body weights.

The new numbers are up significantly from a report last year by an international group that estimated that up to 30 percent of food -- worth about $48.3 billion -- is wasted each year in the United States. Those calculations and others like it were typically based on interviews with people and inspections of garbage, which the NIDDK believes underestimates the waste.

Food waste also contributes to excess consumption of freshwater and fossil fuels which, along with methane and carbon dioxide emissions from decomposing food, impacts global climate change.

Despite all the waste, many Americans are still going hungry. A recent report by the Department of Agriculture found the number of U.S. homes lacking "food security," meaning their eating habits were disrupted for lack of money, rose from 4.7 million in 2007 to 6.7 million last year.

About 1 billion people worldwide don't have enough to eat, according to the World Food Program .