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Scientists say eating your leftovers is good for you and the environment

Sep 9, 2014

Credit User: Kathleen Franklin/Flickr

Researchers have found that food waste has a big impact on the heat-trapping gasses we release into the environment.

Marty Heller is a senior research specialist with the Center for Sustainable Systems at the University of Michigan.

In a new study, he and U of M's Greg Keoleian looked at the greenhouse gas emissions involved with the production of the food we eat and the food we waste.

“If we look at the greenhouse gas emissions associated with that food waste, it is equivalent to adding an additional 33 million average passenger vehicles to our roads every year,” Heller said.

"If we look at the greenhouse gas emissions associated with that food waste, it is equivalent to adding an additional 33 million average passenger vehicles to our roads every year." - 2014 Marty Heller, study's co-author

Heller and Keoleian studied the emissions associated with about 100 different types of food. They discover that certain types of foods have the highest greenhouse gas emissions associated with their production.

"Typically we see a very distinct difference between foods that are animal based — meats, dairy —and foods that are plant based," Heller said.

"To a large extent that's because of the additional feed that is required to keep an animal alive and sort of their conversion efficiency of the feed that they consume."

He also found that some of those animals, cows in particular, emit a great deal of methane which is a very potent greenhouse gas emission.

USDA dietary guidelines help and hurt

The most recent dietary guidelines from the USDA say we should be eating more fruits and vegetables, more low-fat dairy products and seafood. And in this country we eat more meat than the guidelines say that we should.

One of the things they looked at is what would happen to greenhouse gas emissions if we shifted our diets to match what the USDA recommends.

"We found that if we were to maintain the same level of caloric intake as we do with our current diet that the greenhouse gas emission associated with our production of that food would increase by about 12%," Heller said.

He emphasized that the average person eats too many calories, according to those recommendations.

"On average we should decrease our caloric intake by about 20% according to those recommendations. The recommendations end up calling for lower intake of meats, which carry large carbon footprint, but they also call for an increase in dairy consumption. " he said. "And dairy productions also tends to be greenhouse gas intensive."

They found the tradeoff is close to a wash.

Benefits to cutting back on food waste

Heller's research found that the amount of food that we waste is roughly equivalent in greenhouse gas emissions to the savings the U.S. would realize, as a country, going to a completely vegetarian diet. He admits that neither of those scenarios is realistic for the U.S. right now.

"But combined (reducing our food waste and perhaps reducing the amount of meat that we consume) can lead to very significant decreases in greenhouse gas emissions associated with our food system."

Heller added that the reduction would be "upwards of 30% reduction."